How to open a PDF, add text & an image, and save it as a new file

var img = new Bitmap(@"image.jpg");
using (var reader = new PdfReader("in.pdf", dpi, dpi))
using (var frame = reader.Frames[0])
using (var container = frame.GetContent())
using (var writer = new PdfWriter("out.pdf"))
{
       writer.AddPage(pageWidth, pageHeight, dpi, dpi);
       using (var graphics = writer.GetGraphics())
       {
              graphics.DrawImage(frame.GetBitmap(), new System.Drawing.RectangleF(0, 0, frame.Width, frame.Height));
              graphics.DrawImage(img, new System.Drawing.RectangleF(0, 0, imgWidth, imgHeight));
              var plainText = new PlainText("Some text", graphics.CreateFont("Arial", 16), new System.Drawing.PointF(20, 30));
              graphics.DrawText(plainText);
       }
 }