Hi! I am a graduate student at UMass, but I don't really have a lot of information for you. My sorority is not a part of the UMass Greek system, so we hold our recruitment at a different time than the University sororities. The fliers that I have seen seem to indicate that you simply come at the posted times. You should be able to contact sorority officers directly by looking at the listings on the UMass website. They will be able to give you better direction.
I'm glad that you are interested in learning more about Greek life at UMass. Good luck, and keep us posted on your progress.
Erica