protected void btnCreatePDF_Click(object sender, EventArgs e)
{
    // create a PDF document
    Document document = new Document();

    // set the license key
    document.LicenseKey = "B4mYiJubiJiInIaYiJuZhpmahpGRkZE=";

    // add a page to the PDF document
    PdfPage firstPage = document.AddPage();

    string imagesPath = System.IO.Path.Combine(Server.MapPath("~"), "Images");

    // display image in the available space in page and with a auto determined height to keep the aspect ratio
    ImageElement imageElement1 = new ImageElement(0, 0, System.IO.Path.Combine(imagesPath, "evologo-250.png"));
    AddElementResult addResult = firstPage.AddElement(imageElement1);

    // display image with the specified width and the height auto determined to keep the aspect ratio
    // the images is displayed to the right of the previous image and the bounds of the image inside the current page
    // are taken from the AddElementResult object
    ImageElement imageElement2 = new ImageElement(addResult.EndPageBounds.Right + 10, 0, 100,
            System.IO.Path.Combine(imagesPath, "evologo-250.png"));
    addResult = firstPage.AddElement(imageElement2);

    // Display image with the specified width and the specified height. It is possible for the image to not preserve the aspect ratio 
    // The images is displayed to the right of the previous image and the bounds of the image inside the current page
    // are taken from the AddElementResult object
    ImageElement imageElement3 = new ImageElement(addResult.EndPageBounds.Right + 10, 0, 100, 50,
            System.IO.Path.Combine(imagesPath, "evologo-250.png"));
    addResult = firstPage.AddElement(imageElement3);

    try
    {
        // get the PDF document bytes
        byte[] pdfBytes = document.Save();

        // send the generated PDF document to client browser

        // get the object representing the HTTP response to browser
        HttpResponse httpResponse = HttpContext.Current.Response;

        // add the Content-Type and Content-Disposition HTTP headers
        httpResponse.AddHeader("Content-Type", "application/pdf");
        httpResponse.AddHeader("Content-Disposition", String.Format("attachment; filename=ImageElement.pdf; size={0}", pdfBytes.Length.ToString()));

        // write the PDF document bytes as attachment to HTTP response 
        httpResponse.BinaryWrite(pdfBytes);

        // Note: it is important to end the response, otherwise the ASP.NET
        // web page will render its content to PDF document stream
        httpResponse.End();
    }
    finally
    {
        // close the PDF document to release the resources
        document.Close();
    }
}