Setting aim on headlights

Going to put a new set of halogens in the Kenworth, looked around at a bunch, still like the looks of the the Bosch but at $65 each i'll pass, Crystal Clear lights are almost $100 per pair and i am a little nervous to buy sight unseen so i guess i'll get a set of Sylvania Extra Vision, around $15 each but when i read my post from below i really should check the aiming of them, after we had it painted they could be out and more then likely is maybe a little of the problem, still dull and a little yellow so its time for new ones. So how exactly is the correct aiming of the headlights done, i remember something about shining the lights at a door from so many feet back and they should be up a certain heigth, any help here would be appreciated, thanks again. Thanks for all replies to my last question of headlights too, lots of good knowledgable people here, really appreciate you all.

 

Perfect, thats exactly what i was looking for, thanks very much lostNfound and vegetto05, really appreciate both your help.