Congratulations! By now you've learned how easy it is to create a visually engaging spot from scratch using the extremely versatile Solid layer:
Since After Effects 6.5 treats solids like any other footage in the Project window, you can easily replace a solid with footage. Try replacing the Mid colored background layers with a moving texture or some footage.
The mattes you've created allow you to put different items over the backdrop. Experiment by replacing the still image with video, or by adding an animated logo over the moving texture.