The sample demonstrates how to add worksheet in Excel workbook via Spire.XLS.

using System.Drawing;
using System.Data;
using System.Data.OleDb;

using Spire.Xls;

namespace AddSheet
{
    class Program
    {
        static void Main(string[] args)
        {
            Workbook workbook = new Workbook();
            workbook.LoadFromFile(@"..\..\..\..\Data\parts.xls");

            //add one worksheet to workbook
            workbook.CreateEmptySheet("NewSheet");
            
           //set the new sheet's context
            Worksheet sheet = workbook.Worksheets[1];
            string connString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=..\\..\\..\\..\\Data\\database.accdb;Persist Security Info=False;";
            string sqlCountry="select * from vendors";
            DataTable vendor = new DataTable();
            using (OleDbConnection conn = new OleDbConnection(connString))
            {
                OleDbDataAdapter adapter = new OleDbDataAdapter(sqlCountry, conn);
                adapter.Fill(vendor);
            }
            sheet.InsertDataTable(vendor, true, 1, 1);

            //set the style of the new sheet
            sheet.AllocatedRange.AutoFitColumns();
            sheet.Range[1, 1, 1, vendor.Columns.Count].Style.Color = Color.DeepSkyBlue;
            sheet.Range[1, 1, 1, vendor.Columns.Count].Style.Font.IsBold = true;
            sheet.Range[1, 1, 1, vendor.Columns.Count].HorizontalAlignment = HorizontalAlignType.Center;
            sheet.Range[2, 1, vendor.Rows.Count + 1, vendor.Columns.Count].Style.Color = Color.SkyBlue;
            sheet.AllocatedRange.Style.Borders.LineStyle = LineStyleType.Thin;
            sheet.AllocatedRange.Borders[BordersLineType.DiagonalDown].LineStyle = LineStyleType.None;
            sheet.AllocatedRange.Borders[BordersLineType.DiagonalUp].LineStyle = LineStyleType.None;
                 
            workbook.SaveToFile("sample.xls", ExcelVersion.Version97to2003);
            System.Diagnostics.Process.Start(workbook.FileName);
        }
    }
}

Imports System.Drawing
Imports System.Data
Imports System.Data.OleDb

Imports Spire.Xls

Namespace AddSheet
	Class Program
		Private Shared Sub Main(args As String())
			Dim workbook As New Workbook()
			workbook.LoadFromFile("..\..\..\..\Data\parts.xls")

			'add one worksheet to workbook
			workbook.CreateEmptySheet("NewSheet")

			'set the new sheet's context
			Dim sheet As Worksheet = workbook.Worksheets(1)
			Dim connString As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=..\..\..\..\Data\database.accdb;Persist Security Info=False;"
			Dim sqlCountry As String = "select * from vendors"
			Dim vendor As New DataTable()
			Using conn As New OleDbConnection(connString)
				Dim adapter As New OleDbDataAdapter(sqlCountry, conn)
				adapter.Fill(vendor)
			End Using
			sheet.InsertDataTable(vendor, True, 1, 1)

			'set the style of the new sheet
			sheet.AllocatedRange.AutoFitColumns()
			sheet.Range(1, 1, 1, vendor.Columns.Count).Style.Color = Color.DeepSkyBlue
			sheet.Range(1, 1, 1, vendor.Columns.Count).Style.Font.IsBold = True
			sheet.Range(1, 1, 1, vendor.Columns.Count).HorizontalAlignment = HorizontalAlignType.Center
			sheet.Range(2, 1, vendor.Rows.Count + 1, vendor.Columns.Count).Style.Color = Color.SkyBlue
			sheet.AllocatedRange.Style.Borders.LineStyle = LineStyleType.Thin
			sheet.AllocatedRange.Borders(BordersLineType.DiagonalDown).LineStyle = LineStyleType.None
			sheet.AllocatedRange.Borders(BordersLineType.DiagonalUp).LineStyle = LineStyleType.None

			workbook.SaveToFile("sample.xls", ExcelVersion.Version97to2003)
			System.Diagnostics.Process.Start(workbook.FileName)
		End Sub
	End Class
End Namespace

The sample demonstrates how to Add Column in Excel workbook via Spire.XLS.

using System.Drawing;
using System.Data;
using System.Data.OleDb;
using Spire.Xls;

namespace AddColumn
{
    class Program
    {
        static void Main(string[] args)
        {
            Workbook workbook = new Workbook();
            workbook.LoadFromFile(@"..\..\..\..\Data\parts-column.xls");
            Worksheet sheet = workbook.Worksheets[0];

            //add one column
            sheet.InsertColumn(3);

            //get the data of the new column
            DataColumn dataColumn = GetColumnData(4);

            //insert the data into the new column
            sheet.InsertDataColumn(dataColumn, true, 1, 3);

            //add two columns
            sheet.InsertColumn(5, 2);

            //get the data of the two new columns
            DataColumn dataColumn4 = GetColumnData(5);
            DataColumn dataColumn5 = GetColumnData(6);

            //insert the data into the new columns
            sheet.InsertDataColumn(dataColumn4, true, 1, 5);
            sheet.InsertDataColumn(dataColumn5, true, 1, 6);

            int rowCount = 0;
            rowCount = sheet.Rows.Length;
            //set the added columns's style
            SetFormat(sheet, 3,rowCount);
            SetFormat(sheet, 5,rowCount);
            SetFormat(sheet, 6,rowCount);

            workbook.SaveToFile("sample.xls", ExcelVersion.Version97to2003);
            System.Diagnostics.Process.Start(workbook.FileName);
        }
        static private DataColumn GetColumnData(int columnIndex)
        {
            string connString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=..\\..\\..\\..\\Data\\database.accdb;Persist Security Info=False;";
            DataTable parts = new DataTable();
            using (OleDbConnection conn = new OleDbConnection(connString))
            {
                string sqlParts = "select * from parts";
                OleDbDataAdapter adapter = new OleDbDataAdapter(sqlParts, conn);
                adapter.Fill(parts);
            }
            DataColumn column = parts.Columns[columnIndex];
            return column;
        }

        static private void SetFormat(Worksheet sheet, int columnIndex,int rowCount)
        {
            //set the header style
            sheet.Range[1, columnIndex].Style.Font.IsBold = true;
            sheet.Range[1, columnIndex].Style.Color = Color.DeepSkyBlue;
            sheet.Range[1, columnIndex].HorizontalAlignment = HorizontalAlignType.Center;
            sheet.Range[1, columnIndex].AutoFitColumns();

            //draw the lines
            sheet.Range[1, columnIndex, rowCount-1, columnIndex].Style.Borders.LineStyle = LineStyleType.Thin;
            sheet.Range[1, columnIndex, rowCount-1, columnIndex].Borders[BordersLineType.DiagonalDown].LineStyle = LineStyleType.None;
            sheet.Range[1, columnIndex, rowCount-1, columnIndex].Borders[BordersLineType.DiagonalUp].LineStyle = LineStyleType.None;

            //set the data rows's color
            sheet.Range[2, columnIndex, rowCount-1, columnIndex].Style.Color = Color.SkyBlue;
        }
    }
}

Imports System.Drawing
Imports System.Data
Imports System.Data.OleDb
Imports Spire.Xls

Namespace AddColumn
	Friend Class Program
		Shared Sub Main(ByVal args() As String)
			Dim workbook As New Workbook()
			workbook.LoadFromFile("..\..\..\..\Data\parts-column.xls")
			Dim sheet As Worksheet = workbook.Worksheets(0)

			'add one column
			sheet.InsertColumn(3)

			'get the data of the new column
			Dim dataColumn As DataColumn = GetColumnData(4)

			'insert the data into the new column
			sheet.InsertDataColumn(dataColumn, True, 1, 3)

			'add two columns
			sheet.InsertColumn(5, 2)

			'get the data of the two new columns
			Dim dataColumn4 As DataColumn = GetColumnData(5)
			Dim dataColumn5 As DataColumn = GetColumnData(6)

			'insert the data into the new columns
			sheet.InsertDataColumn(dataColumn4, True, 1, 5)
			sheet.InsertDataColumn(dataColumn5, True, 1, 6)

			Dim rowCount As Integer = 0
			rowCount = sheet.Rows.Length
			'set the added columns's style
			SetFormat(sheet, 3,rowCount)
			SetFormat(sheet, 5,rowCount)
			SetFormat(sheet, 6,rowCount)

			workbook.SaveToFile("sample.xls", ExcelVersion.Version97to2003)
			System.Diagnostics.Process.Start(workbook.FileName)
		End Sub
		Private Shared Function GetColumnData(ByVal columnIndex As Integer) As DataColumn
			Dim connString As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=..\..\..\..\Data\database.accdb;Persist Security Info=False;"
			Dim parts As New DataTable()
			Using conn As New OleDbConnection(connString)
				Dim sqlParts As String = "select * from parts"
				Dim adapter As New OleDbDataAdapter(sqlParts, conn)
				adapter.Fill(parts)
			End Using
			Dim column As DataColumn = parts.Columns(columnIndex)
			Return column
		End Function

		Private Shared Sub SetFormat(ByVal sheet As Worksheet, ByVal columnIndex As Integer, ByVal rowCount As Integer)
			'set the header style
			sheet.Range(1, columnIndex).Style.Font.IsBold = True
			sheet.Range(1, columnIndex).Style.Color = Color.DeepSkyBlue
			sheet.Range(1, columnIndex).HorizontalAlignment = HorizontalAlignType.Center
			sheet.Range(1, columnIndex).AutoFitColumns()

			'draw the lines
			sheet.Range(1, columnIndex, rowCount-1, columnIndex).Style.Borders.LineStyle = LineStyleType.Thin
			sheet.Range(1, columnIndex, rowCount-1, columnIndex).Borders(BordersLineType.DiagonalDown).LineStyle = LineStyleType.None
			sheet.Range(1, columnIndex, rowCount-1, columnIndex).Borders(BordersLineType.DiagonalUp).LineStyle = LineStyleType.None

			'set the data rows's color
			sheet.Range(2, columnIndex, rowCount-1, columnIndex).Style.Color = Color.SkyBlue
		End Sub
	End Class
End Namespace