I got a new set of bulbs the other day (Wagner Truview #BP9007TV).....and decided to re-adjust the aim slightly to take advantage of the better lighting.
There are two different ways to do this.....the first way is by the book, using generic specs for the Focus, against a target. This way can be done any time of the day (unless you are outside in bright sunlight), and is the method used by most dealers. It works ok.....but you can do better.
That's showing this method, except for a measured spot (I used the door panels as a mark). Start by finding a wall or garage door......and two marks of some sort at the same height. The best way is to have about a half-tank of fuel, your normal stuff in the trunk, and the tires at their correct pressure. If you have to do this more than once, be sure the car is at the same distance from the same wall, with the same marks.
How exactly you want the adjustment.....there are no absolutes. It depends on your normal driving. In town you might want the aim lower. If you do mostly highway, you might want the aim higher. How high depends also on your vision, and the brightness of the headlights. Adjust too high, and you won't be able to see the road surface.
I prefer to have the passenger side slightly higher than the driver side....shows up the side of the road better, without irritating on-coming cars. This is also a method to tell if the aim of either headlight is too high. If you get a lot of people flashing at you.....you're too high, or your bulbs glare too much.
The Focus has no side-to-side adjustment...only an up-down adjustment. It's done easily using an allen wrench on each side. Watch the beam change as you turn the wrench....counter-clock-wise makes the beams go up. Small turns with this adjustment make a big difference. I suggest 1/2 turns of the wrench, after-which you road-test at night. Try to find roads with little traffic, and a variety of terrain.
Ok the second method......the quickest method, but with some danger. Forget the wall method. Do everything at night. Drive the car and note where each beam falls. Stop, adjust the beams, and re-test. Just don't get hit by somebody. You can do this in a few minutes. I normally do my own cars like this. If you're working in the day-time, you'll have to use the wall/mark method. The second method will give better results.....Be careful.