//make the borders of cell F6 thick
worksheet.Cells[6, 6].Style.Border.Top.Style = ExcelBorderStyle.Thick;
worksheet.Cells[6, 6].Style.Border.Right.Style = ExcelBorderStyle.Thick;
worksheet.Cells[6, 6].Style.Border.Bottom.Style = ExcelBorderStyle.Thick;
worksheet.Cells[6, 6].Style.Border.Left.St...