Frames and .NET WebBrowser Control HELP!

I have a form with two labels, a button and the .Net WebBrower Control on it.
My goal is to send the contents of the labels to fields on the asp form in the webbrowser control.
The following code does that just fine, but the actual form on the website I need to use, uses a top frame for navigation links!
When I try to send stuff to the webform it acts like it can only see the upper navigational frame and it wont fill out the form in the lower frame :(

How can I adjust the following code to send my stuff to that lower frame that contains the actual webform?

Thanks for any help.

Code******************************
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        AxWebBrowser1.Navigate2("http:\\www.thiswebsitewithaform.com")
    End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click

        Dim FirstName As String
        Dim LastName As String
       
        FirstName = lblFirstName.Text
        LastName = lblLastName.Text
       
        With AxWebBrowser1
            Do While Not mblnDownloadCompleted
                Application.DoEvents()
            Loop
            .Document.All("app_first_name").Value = FirstName
            .Document.All("app_last_name").Value = LastName
           

            Do While Not mblnDownloadCompleted
                Application.DoEvents()
            Loop
        End With
    End Sub