Doesn't the pat have disc brakes in the rear? That means you just replacing the pads (why would you do rotors already?) isn't going to solve it. Pull the rotors off the rear and I'd expect you to find a tiny drum brake mechanism in there. Hopefully you just need new shoes on that and you'll be fine. If those look ok, then maybe the cable stretched. I've never done it but I'd think behind the drum brake mechanism there would be a place where you can adjust the parking brake cable.
EDIT: I just spotted the bit about you never having done a brake job before. Doing disc brakes is stupid easy, but fixing the parking brake gets more involved. Take apart one side, pull the caliper and then the disc. That should expose the drum brake for the parking brake. The only thing I remember about working on drum brakes is that they are annoying. If looks scary, at this point it's easy to put it back together and drive it to a place like brakes plus.