To put it succinctly, you should go to vista elearning (http://vista.elearning.unsw.edu.au/webct/entryPage.dowebct) then click on your course for e.g. EDST1101 Educational Psychology I. This will be on the home page if you have enrolled for this via my.unsw.
Once you enter your course sub-site, just look for some links such as 'lectopia', 'course material' or 'resources'. You should be there.
Whether you can listen to an iLecture depends on whether you're getting taught in CATS rooms and some lecturers are too lazy to put up their powerpoints presentations.