What yr is your CTS?? Is it HID equipped or Halogen??
I only ask about the yr just in case because 03 Halogen equipped CTS's have those sign spotters a.k.a Squirrel finders so adjusting is difficult because u can cause glare whether u adjust them up or down.
But 04 Halogens or any yr HID equipped its pretty simple. Wish I had a photo to diagram but right above the headlights there are two holes with adjustment screws. The right one (with the white collar around the screw) is the vertical adjustment, the left is the horizontal adjustment. You'll need an allen wrench also.
For HID's (probably just as good for halogens) best way to make sure you get the correct adjustment is to first get on flat level ground, pull about 25 ft from a wall (light colored wall if possible). Measure the height from the ground to the middle of the projector. Then u want to adjust the headlight beam pattern about 1.5" to 2" below that measurement.
Appearances may be deceiving. The low beam has such a sharp cutoff at the top it may look to you like it is bright for other drivers but this is not the case. If I were you I would leave the headlight aiming job to a professional with the correct instrumentation.