There are two ways of aiming lights. One, professionals use specialized equipment like the expensive Hella European light aiming machine. These machines are few and far between, only a few dedicated European tuners have them on this side of the Atlantic. The operation is quite simple; the machine is placed in front of the car and is aligned with the center of the headlamp, then the machine is set for a declining gradient (1.2% for cars). The lights are turned on and adjusted until the beam image lines up with the alignment marks in the aiming machine. This is the best method for aiming headlamps, but since it is unlikely that one is available locally, the second option is to aim them yourself.
To aim your headlamps yourself, all that is required is a vertical wall and 25 feet of level ground in front. Park the car next to the wall and mark a line on the wall at the horizontal and vertical centers of the headlamps (black electrician’s tape works well). This is the center-point. Next mark a horizontal line 3½ inches below the center mark. Back the car 25 feet straight back and turn on the low beams. Turn the left/right adjusting screw until the bright spot is inline with the vertical center mark. Then turn the up/down adjusting screw until the beam cut-off is inline with the lower horizontal line. Repeat for the other side. Its interesting to note that 3½ inches of vertical drop in 25 feet works out to a 1.2% gradient. If your headlamp unit has the low and high beams integrated, then you're finished. If your car has a separate high beam unit, then they should be aimed as well. Follow the same procedure, cover the low beams with a piece of cardboard (if both illuminate simultaneously), turn on the high beams and turn the adjusting screws until the brightest spot is inline with the center-point mark. Now you're done and you can enjoy your new lights!
