Choose a background and put a colored rectangle on the bottom of the screen:
Go back and edit the code on the ball to match the color stripe you painted.
Finishing up you need a background and background music.
You can find music under "Loops" in scratch or the Sounds category on my website.
After you have your music, add this code to make it play continuously:
Finally make sure you name your game and include directions. PLAY YOUR GAME and comment on your high score. You can also add it to the studio so others in the class can play your game: https://scratch.mit.edu/studios/1005380