you start your way up in your 3dig year. you can hold one of many "clerk" positions: basically, you're the brunt of all the work.. i once had it explained to me like this:
firsties come up with these elaborate, excellent, perfect, flawless plans on how to make usafa better. they then pass it along to the two degrees to figure out exactly what needs to be done to get the firsties' plans right. the 2 digs give it to the 3 digs to implement, and EVERYONE yells at the 4digs for it not working
now of course that's all an exaggeration, but somewhat applicable. 3 dig year, you're learning how to do some of the 2 dig jobs, and you start out small. organizing squadron/ group CQ duties (chief clerk), on training staff helping out the training officer and nco dealing with freshmen (training clerk) or helping squad morale stay high (MWR clerk). you learn how to put things together.
2 dig year, you have a million more options, from element leader all the way up to chief msgt for the wing. there are tons of opportunities, from organizing things to working with people.
firstie year is the same way, but on the officer side. you head up pretty much everything: MWR (morale, welfare, readiness i think), airmanship, flight/squadron officer positions, group positions, wing positions, everything. there are, again, 12 million different things to do. all depends on what you want and what you're willing to try for