There is no lining up to do. All parts, once installed correctly are aligned. If it seems like it's coming off the alternator pulley, then check to see if the alternator is in alignment. Why don't you take it back to the mechanic who did the job? That should be his problem to resolve, not yours, since it wasn't doing that before he messed with it. Besides, it really doesn't sound like mechanics are your type of thing, like you said.