The best you can do is install something like UltraVNC in full screen mode and clone your display onto your laptop screen. But you generally can't connect your desktop to your laptop unless you had a tv tuner card on your laptop.
TV TUNER:
Plug in your desktops TV-out into your laptops tv tuner.
VNC:
Install VNC server on desktop.
Run VNC viewer in full-screen mode on laptop.