You can use like this to extract source of a web page:
Dim inputUrl As String = "http://google.com/"
Dim stream As System.IO.Stream
Dim myRequest As System.Net.WebRequest = System.Net.WebRequest.Create(str1)
Dim resp As System.Net.WebResponse = myRequest.GetResponse
stream = resp.GetResponseStream
srRead = New System.IO.StreamReader(stream)
Dim outputHtml As String = srRead.ReadToEnd