Web Forms :: Post Data To Page

I've got a web page that will have information passed to it, and after doing some checking it will log the user that was passed to into a secure site. Currently I've got the code below working, it actually posts the respected page and logs me in. Howevever, the problem arises after it the login page appears. Instead of the url in the address bar of explorer showing the web address of the page I'm on it shows the web address of page that sent me to the log in. Is there any way using this code (or another set of code) that will allow me to do this? This is part of a single sign on project, and most of this is pretty new to me.

Dim postData =
String.Format("my post data")
Dim data
As String = postData
Dim uri
As New
Uri("my web address")
If uri.Scheme = uri.UriSchemeHttp
Then
Dim request
As HttpWebRequest =
HttpWebRequest.Create(uri)
request.Method =
WebRequestMethods.Http.Post
request.ContentLength = data.Length
request.ContentType =
"application/x-www-form-urlencoded"
Dim writer
As New
StreamWriter(request.GetRequestStream)
writer.Write(data)
writer.Close()
Dim oResponse
As HttpWebResponse = request.GetResponse()
Dim reader
As New
StreamReader(oResponse.GetResponseStream())
Dim tmp
As String = reader.ReadToEnd()
oResponse.Close()
Response.Write(tmp)
Exit Sub
End
If

Update: Ok, it seems as though the method above is "scraping" the response from the web page and placing it on my page. This isn't what
I want. I want to post the data and actually go to that page.