The aiming knobs are generally something not to be messed with. The knob I mentioned is a hollow black plastic knob on top of the high beam pod and right next to the low beam pod. The knob will adjust both of them simultaneously. It is used to raise or lower the beams. I will not describe the location of the knob used to adjust the lights horizontally. You can really screw things up with this one, and it rarely needs to be changed.
Headlight aiming is usually best left to professionals, unless like me the professional screwed it up worse than the factory. There are several web sites which give instructions for you di-it-youselfers. That is how I re-aimed my lights after the dealer left one of them pointing at the moon. My car came from the factory with the headlights aimed way below spec. I asked the dealer to fix it and one headlight ended up just under spec, and the other was more useful for illuminating low flying UFO's than lighting up the road.