APP advertising help????!?

[Areesah]

ok so in school in IT we have to create an app for smartphones and the best one in my current year will get published to the apple app store and im stuck on how i should advertise my app.My app is a rubicks cube type but way better and more better features-like u can play online with people around the world-differnt shapes-different designs and more.At the moment im thinking of doing a huge poster advertising it and in the background have the rubicks theme of bright ,colourfurful.In other words iknow how to present it but i need help on what to have on it and how it will catch peoples eyes and make it persuasive??? HELP? please