Resources

Representational is an art work that contains recognizable images.
These images can be realistic in nature, or they can be more abstract.
You should work freehand with the mouse and, use Photoshop the same way you would use conventional painting methods.

Some ideas for your image:
landscapes, people, sports events, comic characters, still lifes, figures in action, spacescapes, self portraits, ect.

Non-Representational: an image that does not contain recognizable elements. It usualy contains abstract shapes either organic or geometric.

Geometric: an image that consists of mostly geometric shapes (circles, squares, triangle and the like)