Now that you know how to load and display a background image in Rubygame, it's time to move onto other graphics, like sprites. A sprite is a smaller graphic displayed on the screen, usually representing the part of the game like the player's ship in Space Invaders or Pac-man in any of the Pac-man games. Backgrounds usually remain static, while sprites can move around and be animated.
Before getting started, be sure to download the part 2 example files. This is a different file than the previous articles, so you'll need to download the file linked to above.