add footer for each page in the pdf document

public partial class Footer : PdfPageEventHelper
{
public override void OnEndPage(PdfWriter writer, Document doc)
{
Paragraph footer= new Paragraph("THANK YOU", FontFactory.GetFont(FontFactory.TIMES, 10, iTextSharp.text.Font.NORMAL));
footer.Alignment = Element.ALIGN_RIGHT;
PdfPTable footerTbl = new PdfPTable(1);
footerTbl.TotalWidth = 300;
footerTbl.HorizontalAlignment = Element.ALIGN_CENTER;
PdfPCell cell = new PdfPCell(footer);
cell.Border = 0;
cell.PaddingLeft = 10;
footerTbl.AddCell(cell);
footerTbl.WriteSelectedRows(0, -1, 415, 30, writer.DirectContent);
}
}

Document document = new Document(PageSize.A4, 50, 50, 25, 25);
var output = new FileStream(Server.MapPath("Demo.pdf"), FileMode.Create);
PdfWriter writer = PdfWriter.GetInstance(document, output);
// Open the Document for writing
document.Open();
//using footer class
writer.PageEvent = new Footer();.
Paragraph welcomeParagraph = new Paragraph("Hello, World!");
document.Add(welcomeParagraph);
document.Close();