Logout option

Question

Hi all,

i am getting stuck in my application..i have included  web browser component in my website for Facebook page..and i have passed the username and password through two text boxes and button to enter into it automatically..it enters but i dunno how to log out from it automatically..can anyone solve my problem...

 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles fb_button.Click

        Dim fb_button As String = Nothing

        For Each element As HtmlElement In WebBrowser1.Document.All

            If InStr(element.Id, "u_0_b") Then

                fb_button = element.Id

            End If

        Next

        WebBrowser1.Document.GetElementById("email").SetAttribute("value", TextBox1.Text)

        WebBrowser1.Document.GetElementById("pass").SetAttribute("value", TextBox2.Text)

        WebBrowser1.Document.GetElementById(fb_button).InvokeMember("click")

    

    End Sub

here is a code which i have used to enter into the webpage through button...what my question is..if i have to include a session?if it is done whether it will automatically log out??please provide me a code for it..