Dryer drum won't turn but heat works

Hi, I hope I can get some answers here so I don’t have to hire a repair person.
My Whirlpool dryer was purchased in 2002 new. It’s been running fine until last week. (ser: mm2718627, type: DWSR-ELE-2406028-cv54)
The dryer drum does not turn but the heat works. Someone on craigslist encouraged me to come to this site, saying he ordered parts here, and he fixed his dryer, same problem, in about 30 minutes.
He said it’s probably the drum belt.
I would like to purchase the drum belt and the Repair-It-Yourself book and have a friend help me fix it. Is this a somewhat easy thing to fix?
Does this sound like it could be just the drum belt or something else as well? I would like to order the parts ASAP so I don’t have to go to the laundromat.

Thanks,
Jodi