A flash background

This quarter, I've started my most anticipated animation course so far. Digital Cell animation. It's basically a flash animation course where the goal is a visual style akin to 50s animation with limited/stylized animation in mind. Perfect for me, right? Right! Our first assignment was to create a background completely within flash (no fancy photoshop texturing here, folks) and incorporate a character into it. It was suggested that we keep in mind our final assignment, a 15 second commercial, and attempt to utilize this background later. So the short explanation is that my commercial will be for a pain reliever medicine, and creatures are probing the person's brain (in a peculiar sci-fi setting) causing the pain. A personified pill will play the hero and eliminate the villains. Sounds stupid, will be stupid, but hopefully entertaining.