If you want to do a DIY job, then there are access holes above each unit allowing the use of a longish screwdriver. One screw adjusts up and down; the other, side to side. However, a DIY job is very inaccurate and fiddly. I've tried it. I would recommend going to an MOT garage and have them set-up your headlights using their alignment machine. I did this. It took 10 minutes and cost me a tenner and I was very happy with the result.