Default Absolutely lost and stuck on CM11.

Hi folks,

So, a friend decided it'd be a great idea to run the CM installer on my GS3...it's a little buggy and I prefer stock because I'm a bit of a noob, but I can't seem to figure out where to begin. I downloaded Odin, and I have Clockwork recovery installed...but when I tried to load on the stock md5 it didn't work, which is probably a good thing because I'm rather lost and I'll brick my phone. It was running the latest TouchWiz (kitkat, I assume?) and it's the AT&T version. I don't have any interest in the warranty matter, just want to get back to normal, easy-to-use TouchWiz. Any help (and by help, I mean a step-by-step tutorial) would be appreciated and I'd be eternally grateful. Thanks.