Microsoft.Office.Interop.Excel.Application ExcelApp = new Microsoft.Office.Interop.Excel.Application();
                        Microsoft.Office.Interop.Excel.Workbook ExcelWorkBook;
                        Microsoft.Office.Interop.Excel.Worksheet ExcelWorkSheet;
                        ExcelWorkBook = ExcelApp.Workbooks.Add(System.Reflection.Missing.Value);
                        ExcelWorkSheet = (Microsoft.Office.Interop.Excel.Worksheet)ExcelWorkBook.Worksheets.get_Item(1);
                        ExcelApp = new Microsoft.Office.Interop.Excel.Application();
                        ExcelApp.Workbooks.Open(Server.MapPath("APP_DATA\\Test.xls"));

                        for (int i = 0; i < GridView1.Rows.Count; i++)
                        {
                            for (int j = 0; j < GridView1.Columns.Count; j++)
                            {
                                ExcelApp.Cells[i + 9, j + 1] = GridView1.Rows[i].Cells[j].Text;
                                //ExcelApp.Cells.HorizontalAlignment = Microsoft.Office.Interop.Excel.XlHAlign.xlHAlignLeft;
                                ExcelApp.Cells[i + 9, j + 1].Borders.LineStyle = Microsoft.Office.Interop.Excel.XlLineStyle.xlContinuous;
                            }
                        }
                        ExcelApp.Visible = true;
                        ExcelApp.UserControl = true;