How to export data to multiple sheets

// Export DataTable into an excel file with field names in the header line
    // - Save excel file without ever making it visible if filepath is given
    // - Don't save excel file, just make it visible if no filepath is given
    public static void ExportToExcel(this DataTable Tbl, string ExcelFilePath = null)
    {
        try
        {
            if (Tbl == null || Tbl.Columns.Count == 0)
                throw new Exception("ExportToExcel: Null or empty input table!\n");

            // load excel, and create a new workbook
            Excel.Application excelApp = new Excel.Application();
            excelApp.Workbooks.Add();

            // single worksheet
            Excel._Worksheet workSheet = excelApp.ActiveSheet;

            // column headings
            for (int i = 0; i < Tbl.Columns.Count; i++)
            {
                workSheet.Cells[1, (i+1)] = Tbl.Columns[i].ColumnName;
            }

            // rows
            for (int i = 0; i < Tbl.Rows.Count; i++)
            {
                // to do: format datetime values before printing
                for (int j = 0; j < Tbl.Columns.Count; j++)
                {
                    workSheet.Cells[(i + 2), (j + 1)] = Tbl.Rows[i][j];
                }
            }

            // check fielpath
            if (ExcelFilePath != null && ExcelFilePath != "")
            {
                try
                {
                    workSheet.SaveAs(ExcelFilePath);
                    excelApp.Quit();
                    MessageBox.Show("Excel file saved!");
                }
                catch (Exception ex)
                {
                    throw new Exception("ExportToExcel: Excel file could not be saved! Check filepath.\n"
                        + ex.Message);
                }
            }
            else    // no filepath is given
            {
                excelApp.Visible = true;
            }
        }
        catch(Exception ex)
        {
            throw new Exception("ExportToExcel: \n" + ex.Message);
        }
    }
}