basically you have a set number of moves, and with these moves you can move 1 square to the left, right, up or down (the possible places to move are marked with a red X).
on the basic purple squares you have a chance of winning extra moves and with those moves you have to try and get to the special coloured/pattern boxes (the prizes are listed before you click to play). these squares give you a guaranteed prize.
when you get to one of the special squares if you have enough moves left you can go off it and then move back on it to gain another prize : )