There are two hex-like bits that come out of the assembly. They are like the head of a bolt, but black and come out from the headlight towards the engine on a 3cm rod. Get a ratchet and socket onto them, and wind them to adjust.
From memory, it was the top one on each headlight that made mine come down. The lower one on each headlight adjusts left/right, not up/down.
It's a good idea to find a carpark with a flat surface and a wall, park about the distance that you SHOULD leave between you and another car, then adjust until your headlights look as if they won't shine through the rear window of the imaginary car. (The lights on the wall should be about waist-height when you have left the right safety distance from the wall)