Workbook workbook1 = new Workbook();
Worksheet worksheet = workbook1.Worksheets.Add("Sheet1");
// 列ヘッダーをいくつか作成します。
worksheet.Rows[1].Cells[1].Value = "Morning";
worksheet.Rows[1].Cells[2].Value = "Afternoon";
worksheet.Rows[1].Cells[3].Value = "Evening";
workbook1.Save(outputStream);