Generate excel sheet from DataBase and save file to path using C# in ASP.Net

Hi all please helpme ,

 how generate to xls and automatic save file to path folder

      private static void get_data()
        {

            SqlConnection conn = new SqlConnection();
            string connectionString = "Initial Catalog=DBMAILS;Data Source=localhost;Integrated Security=SSPI";
            SqlCommand cmd = new SqlCommand("SELECT * FROM TBL_GROUP_MAIL");
            SqlDataAdapter sda = new SqlDataAdapter();
            try
            {
                conn.ConnectionString = connectionString;
                cmd.Connection = conn;
                conn.Open();
                sda.SelectCommand = cmd;

                DataTable dt = new DataTable();
                sda.Fill(dt);

                if (dt.Rows.Count > 0)
                {
                    //string path = Microsoft.SqlServer.Server.MapPath("exportedfiles\\");
                    string path = "D:\\";

                    if (!Directory.Exists(path))   // CHECK IF THE FOLDER EXISTS. IF NOT, CREATE A NEW FOLDER.
                    {
                        Directory.CreateDirectory(path);
                    }

                    File.Delete(path + "laporan.xlsx"); // DELETE THE FILE BEFORE CREATING A NEW ONE.

            Excel.Application objExcel = new Excel.Application(); 
            Excel._Workbook objBook;Excel.Worksheet objSheets;
            object objOpt  = System.Reflection.Missing.Value;

           objBook = objExcel.Workbooks.Add(objOpt);
           objSheets = (Excel.Worksheet)objExcel.Worksheets.Add(objOpt, objOpt, objOpt, objOpt);
             objSheets.Name = "dffsf";



                    // ADD A WORKBOOK USING THE EXCEL APPLICATION.
                    Excel.Application xlAppToExport = new Excel.Application();

                    xlAppToExport.Workbooks.Add();

                    // ADD A WORKSHEET.
                    Excel.Worksheet xlWorkSheetToExport = (Excel.Worksheet)xlAppToExport.Worksheets.Add(Missing.Value, Missing.Value, Missing.Value, Missing.Value);
                    xlWorkSheetToExport.Name="Result";

                    // ROW ID FROM WHERE THE DATA STARTS SHOWING.
                    int iRowCnt = 3;

                    // SHOW THE HEADER.
                    xlWorkSheetToExport.Cells[1, 1] = "LAPORAN";

                    Excel.Range range = xlWorkSheetToExport.Cells[1, 1] as Excel.Range;
                    range.EntireRow.Font.Name = "Calibri";
                    range.EntireRow.Font.Bold = true;
                    range.EntireRow.Font.Size = 20;

                    xlWorkSheetToExport.Range["A1:D1"].MergeCells = true;       // MERGE CELLS OF THE HEADER.

                    // SHOW COLUMNS ON THE TOP.
                    xlWorkSheetToExport.Cells[iRowCnt - 1, 1] = "ID";
                    xlWorkSheetToExport.Cells[iRowCnt - 1, 2] = "GROUP";
                    xlWorkSheetToExport.Cells[iRowCnt - 1, 3] = "EMAIL";

                    int i;
                    for (i = 0; i <= dt.Columns.Count - 1; i++)
                    {
                        xlWorkSheetToExport.Cells[iRowCnt, i] = dt.Columns[i].ColumnName.ToString();
                    }
                    iRowCnt++;
                    for (i = 0; i <= dt.Rows.Count - 1; i++)
                    {

                        xlWorkSheetToExport.Cells[iRowCnt, 1] = dt.Rows[i]["ID"];
                        xlWorkSheetToExport.Cells[iRowCnt, 2] = dt.Rows[i]["ID_Group"];
                        xlWorkSheetToExport.Cells[iRowCnt, 3] = dt.Rows[i]["Email_address"];
                        iRowCnt = iRowCnt + 1;
                    }

                    // FINALLY, FORMAT THE EXCEL SHEET USING EXCEL'S AUTOFORMAT FUNCTION.
                    Excel.Range range1 = xlAppToExport.ActiveCell.Worksheet.Cells[4, 1] as Excel.Range;
                    range1.AutoFormat(ExcelAutoFormat.xlRangeAutoFormatList3);

                    // SAVE THE FILE IN A FOLDER.

                    xlWorkSheetToExport.SaveAs(path + "EmployeeDetails.xlsx");
                    dt.WriteXml("D:/Tests.xls");
                    // CLEAR.
                    xlAppToExport.Workbooks.Close();
                    xlAppToExport.Quit();
                    xlAppToExport = null;
                    xlWorkSheetToExport = null;

                }
            }
            catch (Exception ex)
            {

            }
            finally
            {
                sda.Dispose();
                sda = null;
            }
        }