    private void fillPdfButton_Click(object sender, EventArgs e)
    {
        Cursor = Cursors.WaitCursor;

        string outPdfFile = @"DemoAppFiles\Output\PDF_Editor\Filled_PDF_Form.pdf";
        Document pdfDocument = null;
        try
        {
            // Load the PDF document with a form to fill
            pdfDocument = new Document(pdfFileWithForm);

            // Set license key received after purchase to use the converter in licensed mode
            // Leave it not set to use the converter in demo mode
            pdfDocument.LicenseKey = "4W9+bn19bn5ue2B+bn1/YH98YHd3d3c=";

            // Get the First Name text box field by name from PDF form fields collection and fill a text value
            PdfFormField firstNameTextBoxField = pdfDocument.Form.Fields["firstName"];
            if (firstNameTextBoxField != null)
                firstNameTextBoxField.Value = firstNameTextBox.Text;

            // Get the Last Name text box field by name from PDF form fields collection and fill a text value
            PdfFormField lastNameTextBoxField = pdfDocument.Form.Fields["lastName"];
            if (lastNameTextBoxField != null)
                lastNameTextBoxField.Value = lastNameTextBox.Text;

            // Get the Password text box field by name from PDF form fields collection and fill a text value
            PdfFormField passwordTextBoxField = pdfDocument.Form.Fields["password"];
            if (passwordTextBoxField != null)
                passwordTextBoxField.Value = passwordTextBox.Text;

            // Get the Gender radio buttons group field by name from form fields collection and set the selected value
            PdfFormField genderRadioGroupField = pdfDocument.Form.Fields["gender"];
            if (genderRadioGroupField != null)
                genderRadioGroupField.Value = maleRadioButton.Checked ? "male" : "female";

            // Get the 'I have a car' check box field by name from form fields collection and set the checked status
            PdfFormField haveCarCheckBoxField = pdfDocument.Form.Fields["haveCar"];
            if (haveCarCheckBoxField != null)
                haveCarCheckBoxField.Value = haveCarCheckBox.Checked;

            // Get the 'Vehicle Type' combo box field by name from form fields collection and set the selected value
            PdfFormField vehicleTypeComboBoxField = pdfDocument.Form.Fields["vehicleType"];
            if (vehicleTypeComboBoxField != null)
                vehicleTypeComboBoxField.Value = vehicleTypeComboBox.SelectedItem;

            // Get the Comments multi line text box field by name from PDF form fields collection and fill a text value
            PdfFormField commentsTextBoxField = pdfDocument.Form.Fields["comments"];
            if (commentsTextBoxField != null)
                commentsTextBoxField.Value = commentsTextBox.Text;

            // Flatten PDF form fields if this was requested
            if (flattenPdfFormCheckBox.Checked)
                pdfDocument.Form.FlattenFields();

            // Save the PDF document in a memory buffer
            byte[] outPdfBuffer = pdfDocument.Save();

            // Write the memory buffer in a PDF file
            System.IO.File.WriteAllBytes(outPdfFile, outPdfBuffer);
        }
        catch (Exception ex)
        {
            // The PDF creation failed
            MessageBox.Show(String.Format("Create PDF Document Error. {0}", ex.Message));
            return;
        }
        finally
        {
            // Close the document to stamp
            if (pdfDocument != null)
                pdfDocument.Close();

            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));
        }
    }