private void convertToPdfButton_Click(object sender, EventArgs e)
{
    // Create a HTML to PDF converter object with default settings
    HtmlToPdfConverter htmlToPdfConverter = new HtmlToPdfConverter();

    // Set license key received after purchase to use the converter in licensed mode
    // Leave it not set to use the converter in demo mode
    htmlToPdfConverter.LicenseKey = "fvDh8eDx4fHg4P/h8eLg/+Dj/+jo6Og=";

    // Enable the automatic conversion of the HTML form to a PDF form 
    htmlToPdfConverter.PdfFormOptions.AutoPdfFormEnabled = createPdfFormCheckBox.Checked;

    // Set the submit buttons style
    htmlToPdfConverter.PdfFormOptions.SubmitButtonStyle.BackColor = Color.Beige;

    // Set the style of various types of text boxes
    htmlToPdfConverter.PdfFormOptions.TextBoxStyle.BackColor = Color.AliceBlue;
    htmlToPdfConverter.PdfFormOptions.PasswordTextBoxStyle.BackColor = Color.MistyRose;
    htmlToPdfConverter.PdfFormOptions.MultilineTextBoxStyle.BackColor = Color.AliceBlue;

    // Set the radio buttons style
    htmlToPdfConverter.PdfFormOptions.RadioButtonsGroupStyle.BackColor = Color.AntiqueWhite;

    // Set the checkboxes styles
    htmlToPdfConverter.PdfFormOptions.CheckBoxStyle.BackColor = Color.AntiqueWhite;

    // set the drop down lists style
    htmlToPdfConverter.PdfFormOptions.ComboBoxStyle.BackColor = Color.LightCyan;
            
    Cursor = Cursors.WaitCursor;

    string outPdfFile = @"DemoAppFiles\Output\HTML_to_PDF\Auto_Create_PDF_Forms.pdf";
    try
    {
        byte[] outPdfBuffer = null;

        if (convertHtmlRadioButton.Checked)
        {
            // Convert a HTML string to a PDF document with form fields
            string htmlWithForm = htmlStringTextBox.Text;
            outPdfBuffer = htmlToPdfConverter.ConvertHtml(htmlWithForm, String.Empty);
        }
        else
        {
            // Convert the HTML page to a PDF document with form fields
            string url = urlTextBox.Text;
            outPdfBuffer = htmlToPdfConverter.ConvertUrl(url);
        }

        // Write the memory buffer in a PDF file
        System.IO.File.WriteAllBytes(outPdfFile, outPdfBuffer);
    }
    catch (Exception ex)
    {
        // The HTML to PDF conversion failed
        MessageBox.Show(String.Format("HTML to PDF Error. {0}", ex.Message));
        return;
    }
    finally
    {
        Cursor = Cursors.Arrow;
    }

    // Open the created PDF document in default PDF viewer
    try
    {
        System.Diagnostics.Process.Start(outPdfFile);
    }
    catch (Exception ex)
    {
        MessageBox.Show(String.Format("Cannot open created PDF file '{0}'. {1}", outPdfFile, ex.Message));
    }
}