This is the complete tag of what happens on clicking the Login button. Extract what you need from it:
I think you are looking for:Code:<form action="https://www.mpgh.net/forum/login.php?do=login" method="post" onSubmit="md5hash(vb_login_password, vb_login_md5password, vb_login_md5password_utf, 0)">
Because this will actually submit the form.Code:https://www.mpgh.net/forum/login.php?do=login
But anyways, I've copied it all, so extract according to your needs.