How to convert a .aspx page to PDF and attach to email in VB.NET

I have a Link that opens a ticket on an .aspx page. I need to convert this link to PDF, that is, convert the Boleto to PDF and attach it to the email that I will send via VB. I tried the steps in this tutorial: link

But it only explains how to convert when the HTML is on the same page, and I need to convert another link, which contains the ticket.

I'm using itextSharp, ASP / VB.NET

Could you help me?

Thank you in advance.

=========================================== ====================

I tried it in several ways, this is the last one I tried:

Dim pdfDoc As New Document()
Dim wr As PdfWriter = PdfWriter.GetInstance(pdfDoc, New FileStream(pdfPath,   FileMode.Create))
pdfDoc.Open()
pdfDoc.Add(wr)
pdfDoc.Close()

The exception I get is this: URI formats are not supported.

I need a way to interpret the URL and convert the Boleto to PDF, the examples I found only show how to create a new PDF from the HTML of the page itself. = [

Thank you!