How do you install a serpentine belt on a 1988 Chevy Silverado?

The diagram should be on the fan shroud. If it isn't, draw one before you take it off. It also is in the owners manual. Otherwise go to a used car lot and find a car with a like engine and draw your own schematic,./

To change the belt (and if you have the original type belt tensioner) you need a small oil filter wrench to loosen the belt tensioner to fit the new belt on. Good luck.