Serpentine belt replacement for 91 Cavalier

My father has been trying to figure out how to replace a serpentine belt on a 91 Cavalier but has had no luck. He was able to get it off with my brothers help but they can't fugure out how to put it back on. Any help would be greatly apreciated.

what do u mean the routing of it?

what engine?

I asked what type of egine it is and they said a 4 banger about 1800 cc engine SOH Cam.