header("Location: veriaktar.asp?username=".$username."&email=".$email."&oauth_id=".$oauth_id."&First_name=".$First_name."&Last_name=".$Last_Name."&First_name=".$First_name);
yerine
$xxx = file_get_contents("http://site.com/veriaktar.asp?username=".$_SESSION['username']."&email=".$_SESSION['email']."&oauth_id=".$_SESSION['oauth_id']."&First_name=".$_SESSION['First_name']."&Last_name=".$_SESSION['Last_name']);