convert datagridview in pdf file ... how can i customize datagridview columns during export pdf?

if (!ErrorMessage)
                    {
                        try
                        {
                            PdfPTable pTable = new PdfPTable(Dgv6.Columns.Count);
                            pTable.DefaultCell.Padding = 3;
                            pTable.WidthPercentage = 150;
                            pTable.HorizontalAlignment = Element.ALIGN_LEFT;
                            foreach (DataGridViewColumn col in Dgv6.Columns)
                            {
                                PdfPCell pCell = new PdfPCell(new Phrase(col.HeaderText));
                                pTable.AddCell(pCell);
                            }
                            foreach (DataGridViewRow ViewRow in Dgv6.Rows)
                            {
                                foreach (DataGridViewCell dcell in ViewRow.Cells)
                                {
                                    pTable.AddCell(dcell.Value.ToString());
                                }
                            }
                            using (FileStream fileStream = new FileStream(save.FileName, FileMode.Create))
                            {
                                //Document document = new Document(PageSize.A4, 8f, 16f, 16f, 8f);
                                Document document = new Document(PageSize.A4, 10.10f, 10.10f, 10.10f, 0.0f);
                                PdfWriter.GetInstance(document, fileStream);
                                document.Open();
                                document.Add(pTable);
                                document.Close();
                                fileStream.Close();
                                File_Prn = fileStream.Name;
                            }