Format excel sheet header while exporting from DataGrid

Workbook workbook = new Workbook();
                        
                        // create a worksheet object
                        Worksheet worksheet = new Worksheet("Enterprise_Summary_Reports");
                      
                        // for header
                        foreach (DataGridColumn dgcol in datagrid1.Columns)
                        {
                            worksheet.Cells[0, ColumnCount] = new Cell(dgcol.Header.ToString());
                            
                            CellStyle css = new CellStyle();
                            css.BackColor = (Color)Colors.Red;
                            worksheet.Cells[0, ColumnCount].Style = css;
                            ColumnCount++;
}
// statements for adding rows                         
  workbook.Worksheets.Add(worksheet);
  // get the selected file's stream
  Stream sFile = sDialog.OpenFile();
  workbook.Save(sFile);