Its usually pretty easy, just make sure you figure out which pulley is the right one and as he said its usually a pretty quick job. (assuming its an idler or tensioner pulley.)

A good way to check which one it is, is to take a solid rod or piece of metal (I usually use a socket extension) and press one side against each part that is attached to a pulley while running and press the other side against the front part of your ear. You will be listening for a grinding noise or even knocking. Just basically something that sounds out of the ordinary and different from the rest of them. If it is your AC, power steering, or alternator its going to be a little bit more complicated to fix based on which one. it shouldnt be your harmonic balancer, cuz if it is you got serious problems haha.

Hope you can understand what im telling you to do here, best of luck finding the source!