recruitment

It depends on whether you're going for a fraternity or a sorority. Sororities will usually flyer for panhellenic recruitment which is the main route for getting into a sorority. Fraternities just have rush events, go up to their booth introduce yourself and go to their rush events, if they like you you'll get a bid.

If you are going for a sorority this is how recruitment works:
You'll see every organization out on campus the week leading up to formal recruitment and they'll be handing out flyers about going Greek. During formal recruitment there are rounds of "parties" where you meet girls from each sorority and every day you decide which ones you want to visit again and the sorority members decide which PNM's they want to invite back to get to know better. After a couple rounds all the PNM's receive envelopes with their bids from the sorority they matched best with and you have bid day and everything. This is the link to Panhellenic's website it explains what to wear and other stuff about recruitment as well as the recruitment application.
sacstate.orgsync.com/org/panhellenic