Now that you have a player class, you can create and display a player. There's no way to move him around just yet, he'll just sit there on the screen, see the next article in this series to learn how to do that.
Creating a player is very easy, just call player = Player.new. Drawing the player is just as easy--just call player.draw(screen). However, the order in which you draw things is important, since everything you draw writes over the things you previously drew. If you were to draw the background last it would draw over everything else you've drawn since it takes up the whole screen. Construct the player before your main loop, near where you loaded the background image and, just after you draw your background image, display the player in your main loop.
def main_loop screen = Screen.new [640, 480] queue = EventQueue.new clock = Clock.new clock.target_framerate = 30 background = Surface['background.png'] player = Player.new loop do clock.tick queue.each do|e| return if e.is_a? QuitEvent end background.blit( screen, [0,0] ) player.draw( screen ) screen.update end ensure Rubygame.quit end