Setting a background on iText PDF

Question

My problem is that I need to add a background to an iText PDF file. The background should fill the whole page and is an image.

Please answer quickly. Thanks for your help

Here is the code and I want to place an image in the background.

enter image description here

        Document document = new Document();

        PdfPTable table = new PdfPTable(2);
        PdfPCell Left = new PdfPCell();
        Left.setBorder(0);
        Left.setHorizontalAlignment(Element.ALIGN_CENTER);
        PdfPCell Right = new PdfPCell();
        Right.setBorder(0);
        Right.setHorizontalAlignment(Element.ALIGN_CENTER);

        try {
            PdfWriter.getInstance(document, new 
        FileOutputStream("C:\\Users\\jensh\\Desktop\\QuizErgebnis.pdf"));
        } catch (FileNotFoundException | DocumentException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        document.open();
        com.itextpdf.text.Font font = 
        FontFactory.getFont(FontFactory.COURIER, 16, BaseColor.BLACK);

        try {
            com.itextpdf.text.Image image = 
        com.itextpdf.text.Image.getInstance("bg.jpg");
        } catch (BadElementException | IOException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        
        try {
            Paragraph H1 = new Paragraph("ZERTIFIKAT", font);
            H1.setAlignment(Element.ALIGN_CENTER);
            H1.setSpacingAfter(30);
    
            document.add(H1);
            table.addCell(Left);
            table.addCell(Right);
            document.add(table);

        } catch (DocumentException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        document.close();