' Form-Parameter
    Dim postData As String = "parameter1=wert1&parameter2=wert2"
    Dim requestBytes As Byte() = Encoding.ASCII.GetBytes(postData)
 
 
    Dim req As HttpWebRequest = WebRequest.CreateHttp( _
      "http://www.adresse.de/seite")
    req.Method = "POST" 'POST-Request statt GET senden
 
    req.ContentType = "application/x-www-form-urlencoded" 'Formular-Parameter
    req.ContentLength = requestBytes.Length
 
    Using reqStream As Stream = req.GetRequestStream() 'Request-Bytes schreiben
        reqStream.Write(requestBytes, 0, requestBytes.Length)
    End Using
 
    Using res As HttpWebResponse = req.GetResponse()
        Using resStream = res.GetResponseStream()
            ' Stream lesen...
        End Using
    End Using