i want to create box in pdf using c#

Hi

 i want to create box in header row in  PDF like that and i had write code

 

PdfPTable ClaimaintHeader = new PdfPTable(3);
PdfPCell OurReferenceHeader = new PdfPCell(new Phrase("Our Ref", _font10BoldBlack));
PdfPCell Claimant = new PdfPCell(new Phrase("Claimant", _font10BoldBlack));
PdfPCell ClaiminigFor = new PdfPCell(new Phrase("Claiming For", _font10BoldBlack));

OurReferenceHeader.BorderColor = iTextSharp.text.BaseColor.BLACK;
Claimant.BorderColor = iTextSharp.text.BaseColor.BLACK;
ClaiminigFor.BorderColor = iTextSharp.text.BaseColor.BLACK;


OurReferenceHeader.BackgroundColor = new iTextSharp.text.BaseColor(System.Drawing.Color.LightGray);
Claimant.BackgroundColor = new iTextSharp.text.BaseColor(System.Drawing.Color.LightGray);
ClaiminigFor.BackgroundColor = new iTextSharp.text.BaseColor(System.Drawing.Color.LightGray);

OurReferenceHeader.HorizontalAlignment = Element.ALIGN_LEFT;
Claimant.HorizontalAlignment = Element.ALIGN_LEFT;
ClaiminigFor.HorizontalAlignment = Element.ALIGN_LEFT;