Roller coaster tycoon 3...peep designer?!?!?

how do I go to the peep designer in roller coaster tycoon 3? do i have to buy it? i looked at the little book that comes with the game, it said a lot about the peep designer, but not how to get to it. from the main menu? and if so what on? ahhhhh..im so confused! I hope you can help!!!