The company website should have a good explanation of the rocker styles on it's boards, if you look around a little. If you dont know what a 3-stage rocker is, my guess is that you probably don't want one, they tend to buck a beginning rider on his/her butt. I would suggest you look at a "continuous rocker." These boards tend to be an overall more consistent ride. Just check your site, or go to Hyperlite.com, they tend to have a good explanation.
Hope this helps.