ok so i got the corner lights in and to do that u have to take off the headlight so i did everything but now both of my headlights are pointed up and i know that the left headlight is supposed to be down lower then the right is this a problem and if so how can i fix it by the way the corners and tail lights look sweet...next up tint rims and a bigger amp

 

Pull your Blazer up to within inches of a flat wall on level ground. Mark the center of the light from your low beams on the wall. Back up until the front of the Blazer is 25 feet from the wall. Obviously you want the left beam slightly below the mark and the right beam on the mark.

That will give you a rough alignment.

 

I'll also note that you'll want to have a 1/2 tank or less to do this. Also, here's the aiming criteria (less what was listed above) from AllDataDIY.com:
The top edge of each high intensity zone must be within 50.8 mm (2 in) above to 63.5 (2.5 in) below the horizontal centerlines. The left edge of each high intensity zone must be within 101.6 mm (4 in) to the left or to the right of the vertical centerlines.

I typically will center up the High Intensity zone of the headlamp on the Right headlamp with the vertical centerline, and position the zone for the Left headlamp just to the left of the vertical centerline. This gives a nice uniform spread over the entire road surface. I also always adjust them to be slightly below (~1.5" lower) the horizontal centerline when at 1/2 tank because when I load up the truck, the lights will go higher, but if you rarely load up your truck, then you shouldn't have anything to worry about centering them up to the horizontal centerline.