I just booted into recovery to see what's going on. It looks like I have TWRP 2.2.1 (or something like that), so I've got the latest version of Odin and have downloaded Liquid Jelly Bean for AT&T (
[ROM][AOSP] Unofficial Liquid Jelly Bean 2.0 [Kang] Updated 10-20 RC5! - xda-developers). So I just boot my phone to recovery, wipe it, then install the ROM and that's it?