Mostly you want to read the "Beginner's Guide" document in the internal SE wiki. Jocelyn Simmonds, Neil Ernst, and I have written a fair amount of useful text there. And it's a "wiki", so you can add to it. Here is information about activating your account on the SE wiki.
Some information for summer students in BA 2270 in summer 2009 appears in http://www.cs.toronto.edu/~pocse/summer/