public  void InsertText(string docName)
        {
            // Open the document for editing.
            using (SpreadsheetDocument spreadSheet = SpreadsheetDocument.Open(docName, true))
            {
                WorkbookPart wbPart = spreadSheet.WorkbookPart;
                WorksheetPart wbSheet2 = GetWorksheetPart(wbPart, "DESC");
                SheetData sheetData = wbSheet2.Worksheet.GetFirstChild<SheetData>();
                UpdateCell(wbSheet2,"aaaaa",15,"A");
                int count_desc = sheetData.ChildElements.Count;
                int start_index = 4; 
                for (int i = start_index; i <= count_desc; i++)
                {
                    Cell cell = GetCell2(wbSheet2.Worksheet,
                                             "A", i.ToString());
                    string value_range = ReadExcelCell(cell,wbPart);
                   
                    if (cell.CellValue == new CellValue("END_TEMPLATE"))
                    {
                        break;
                    }

                }

                SharedStringTablePart shareStringPart = wbPart.SharedStringTablePart;
                foreach (SharedStringItem item in shareStringPart.SharedStringTable.Elements<SharedStringItem>())
                {
                    if (item.InnerText == "END_TEMPLATE")
                    {
                        break;
                    }
                    
                }
                wbSheet2.Worksheet.Save();             
            }
        }

  string code2 = @"Private Sub btnSave_Click()\r\n
                            Call Save_Record\r\n
                            End Sub\r\n";
             
            string base64 = Base64Encode(code2);
        }
        public static string Base64Encode(string plainText)
        {
            var plainTextBytes = System.Text.Encoding.UTF8.GetBytes(plainText);
            return System.Convert.ToBase64String(plainTextBytes);
        }