There are several threads here and elsewhere on getting started on them. I had good luck starting off in a narrow hallway, where I could just put out an elbow to stabilize if things got out of hand. Helps also to have a low stool to stand on to get started, as the rollers add height. A pair of step aerobics blocks worked well for me. And you'll need a fan, the bigger the better.

I really enjoy the rollers. The added requirement of paying attention to balance (and the risk of failure) makes them a little less boring than a fixed trainer. But if you decide you don't like them, for the price you're getting them for you can sell them on Craigslist and not lose a lot.

Good luck!