Set the internal margin of excel textbox in C#

using Spire.Xls;
using Spire.Xls.Core.Spreadsheet.Shapes;
namespace SetInternalMargin
{
    class Program
    {
        static void Main(string[] args)
        {
            {

                //load the sample document
                Workbook workbook = new Workbook();
                workbook.LoadFromFile("Sample.xlsx", ExcelVersion.Version2010);

                //get the first worksheet
                Worksheet sheet = workbook.Worksheets[0];

                //add a textbox to the sheet and set its position and size
                XlsTextBoxShape textbox = sheet.TextBoxes.AddTextBox(4, 2, 100, 300) as XlsTextBoxShape;

                //set the text on the textbox
                textbox.Text = "Insert TextBox in Excel and set the margin for the text";
                textbox.HAlignment = CommentHAlignType.Center;
                textbox.VAlignment = CommentVAlignType.Center;

                //set the inner margins of the contents 
                textbox.InnerLeftMargin = 1;
                textbox.InnerRightMargin = 3;
                textbox.InnerTopMargin = 1;
                textbox.InnerBottomMargin = 1;

                //save the document to file
                workbook.SaveToFile("Result.xlsx", ExcelVersion.Version2010);

            }

        }
    }
}