Need help connecting Allen and Heath Zed 10FX to Mac

Hello everyone, Today I just picked up the Allen and Heath Zed 10FX Mixer for my podcast and music recording. I also have a Shure SM 58 and an RCA cable to connect my iPod to the whole set up. I am having trouble with the final step of getting it to connect to the mac though. I ha ve the mic and RCA cable plugged in correctly and the mixer is connected to the Mac via USB cable but in the users manual it says to just turn on the USB Routing but I can't figure out where or what that is. Ifsomeone has some tips please email me at mike@howtobeblind.com. I really appreciate any help everyone. Thanks and take care!