My kid got a leapster 2 for the holidays and a bunch of games with it but, how do you get the game cards to wo?

I've only been able to get the pre downloaded game and art game that were on it already, and the ones online on the site to work....how do I get those card games to function and play?My kid got a leapster 2 for the holidays and a bunch of games with it but, how do you get the game cards to wo?
once you insert the card into the slot, turn the unit off, install the book for the card and then turn the unit on. this should get the unit to read the card.