Just rename the recovery to PC36IMG.zip, and put it on the root of your sdcard. When you boot into your bootloader, it will automatically detect it and ask if you want to flash it, choose yes and your good to go.
I recommend smelkusmod recovery, it's based on amon ra with extra features. It runs extremely well, and it's what I use on my evo 4g.
Sprint GS3 Running TN's Msg and Chubbs