there are Torx screws on the tip and botton of your headlights, They are pretty tuff to get to and its easiest to just take out the parking lights, screw the top one clockwise to adjust the headlight up and vise versa.
I have a 2004 and the adjusters that adjust the up and down are on the top of the houseing and the ones for left and right are on ethe sides of the housings in between the light and the grill. When I adjusted mine I parked about 30 feet from a wall when it was dark and turned the top Torx screws (T20 I think) right to raise the beam and left to lower it. When adjusting for right/left I opened the hood and removed the rubber flap on the sides of the light housings to better access the Torx screw and adjusted for beam right/left. At 30 feet I tried to aim the lights so the beam hit the wall about the same level as the lights are in the truck and the beams are spaced about the same distance apart. I do alot of night driving on the freeways and in the boonies and they seem to be adjusted perfectly. Hope I helpped.