Dim header As String = "Content : Text/html" + Chr(10) + Chr(13) + "enctype:" & _
  "multipart/from-data" + Chr(10) + Chr(13)
Dim encoding As New System.Text.ASCIIEncoding
Dim Adresse As String = _
  "http://server.de?kndnr=1002&name_kunde=MaxMustermann&pw_kunde=Kennwort&acti" & _
  "n=WKE&hookurl="
Dim wwwAdresse As New Uri(Adresse)
Dim DataPost As Object
DataPost = ASCIIEncoding.ASCII.GetBytes("Test")
WebBrowser1.Navigate(wwwAdresse, False, DataPost, header)