WARNING: This page is about a different car, the 2011 Jaguar XKR, 2011 Jaguar XK, 2010 Jaguar XKR, and 2010 Jaguar XK. However, it is still accessible from the selected car via links, so may be relevant.
Open the hood.
Cap
Adjust the headlamps with an Allen Key.
To adjust the second headlamp, repeat the above procedure.