You try to apply this format
Font DateHeading = new Font(FontFactory.GetFont("helvetica", 12, Font.NORMAL));
PdfPTable ExamDetails = new PdfPTable(1);
PdfPCell ExamDateCell = new PdfPCell(new Phrase("Name", DateHeading));
ExamDateCell.BorderWidth = 0;
ExamDateCell.PaddingTop = 10f;
ExamDateCell.HorizontalAlignment = Element.ALIGN_CENTER;
ExamDetails.AddCell(ExamDateCell);
ExamDetails.SpacingBefore = 200;