How do I change headlight in chevy 2500 - 1988 Chevrolet Silverado 2500

You don't change the headlight, you just change the bulb. In the back iof the headlight you will see a nylon socket holder . You squeeze the clip, and turn it counter clockwise and pull it out. Pull the old bulb out, and replace with a new one, being carefull not to touch the glass part of the new bulb with your fingers. The oil on your fingers will leave a finger print, and that will shorten the life of the bulb.