if you have done the light cycle-game, go to the dataspace. then you must fight some heartless and stop the computers. go to the communication room in the i/o tower. but in the hallyway you must fight the hostile program. defeated him go back to hollow bastion and you must defeat demyx. after that you must defeat 1000 heartless (very easy. to less for me). then go to all the worlds again exept disney castle and timeless river (and atlantica). play through those lands (including pride lands) and return to hollow bastion. you will be transported to the pitt cell and from there acces the game grid. no cycling now. just fighting heartless. after that go to the i/o tower again and tron will learn there new moves. then go to the simulation hanger and depart. there you must defeat heartless quick. the solar sailor must be not to heavy.
ask again if you don't get someting!