Removed the alternator and had it repaired. I am not having much success putting the alternator back on the car. The drive belt needs to be loosened in order to secure the alternator but I cannot find how to loosen or tighten the drive belt.

find the belt tensioner. it's small, circular, and contacts the belt, but doesn't drive anything.

try relieving the tension by loosening the retaining bolt. Or use my method: take a crowbar, place it under the tensioner and against a solid object, get some leverage and move the tensioner while sliding the belt onto the pulley.

i dunno if that's a good description, but that's how i do it.