The code bundle includes around 30 starter images. If you want to add your own artwork, here are the specs:

• .gif or .bmp format - be sure .gif images are still, not animated, and .bmp images are saved as 8-bit files
• Images should have a height equal to the number of pixels in your strip, so mine are 36 pixels high
• Image width can vary, but images look best if the width is fairly narrow. Images that are 36 or 72 pixels wide will lay out beautifully on the wheel. Images that are narrower than 36 pixels also look great. For the most precise looking images, scale down in factors of 36 (18, 3, 6, etc).

36 pixels is not very many pixels! Your images will look tiny on your computer screen. There's an art to getting small images to look clear. Think of an icon - they're pixelated when you zoom in but clear from a distance. Icons or geometric shapes look great. 

It's also effective to use the same shape but color-shifted into different hues. That gives a cohesive look to your bike.

If you want to play them in a certain order, use a naming convention that sorts them numerically or alphabetically. 00_adafruit.bmp plays first since it's listed first in the /img folder.