Hi, soon to be 34 here, and trying to get into better shape myself after a few months off from regular work outs. Congrats on your decision to get fit! If you've never done step before your best bet would be to get Cathe's Beginner Step/Body Fusion dvd. I dont believe this comes in VHS. If you only have VHS capability I'd start with Step Heat. Did you purchase the long "club style" step or the shorter version?? You'll need the longer one for Cathe's workouts.
Just a few words of advice...don't do too much too soon, it'll lead to frustration and "throwing in the towel". Plus, Cathe's choreography can be tricky for a beginner. If you find that to be the case, you could always start with another instructor and come back to Cathe. Start out a low step height, such as 4 inches or practice on the floor with no step at all. In addition, dont forget to include resistance training in your quest for fitness!
Welcome and have fun!
Stacy