There are several green screen images and movies on this Makewaves site. have a look at them and see if you can work out how they are created. Add some of your ideas in to the evidence section.
Watch the introductory video. and think about what sort of green screen content you will be creating. It could be a video or a still image. You can get some more ideas from this website.
Get all the things you need together1. Suitable background image2. iPad with the correct app on3. People or objects to be in it.Be creative, save your work and post your evidence here.Good luck film makers.