在VB.net中获取会话

If I have two files, one in PHP and one in VB.net, how could I get the two to work together?

user.php

echo $_SESSION['user'];

and on the VB.net I have this

Dim sourceString As String = New System.Net.WebClient().DownloadString("https://mywebsite.com/user.php")

I would like the vb.net sourceString to be the session echoed in PHP. Is there another way to do this, or could I make the VB code download the string with their default browser so the sessions would be set?