Returning Specific Information From External Websites With VB.net

I have experimented with coding such as follows:

Imports System.Net
Imports System.IO
Imports System.Data
Partial Class Test01
Inherits System.Web.UI.Page
Dim T01String As String
Private Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim WRequest As WebRequest = WebRequest.Create([URL])
Dim WResponse As WebResponse = WRequest.GetResponse()
Dim WStream As Stream = WResponse.GetResponseStream()
Dim WStreamReader As New StreamReader(WStream, Encoding.UTF8)
T01Location = WStreamReader.ReadToEnd()
WResponse.Close()
WStreamReader.Close()
End Sub
End Class


In this example, a stream of data is captured from the Wikipedia website. I am looking for resources/options to assist in (a) returning specific information from a website based on criterion to be stated in the code (rather than the entire unformatted HTML data, for example), and (b) providing a variable value for an entry required for a particular website, then returning the stream based on the result (example: allowing the entry of an address as a variable value and then returning the zip code from the USPS website). Basically, the idea is to find the correct code configuration for allowing "wildcards" when returning a stream of data from a specific website.