Step one: Cut the black crepe paper sheet into strips that are about 1 inch wide and 4-6 inches long. You can make the strips shorter if needed when you start working.
Step two: Brush Mod Podge on one side of the black crepe paper strip. Press the strip onto the larger foam ball. Repeat until the entire ball is covered in black.
Step three: Cut the black crepe paper strips into 1 inch squares. Use Mod Podge to cover the small foam ball with black crepe paper. Smooth out any bumps or wrinkles, and seal the entire ball with another application of Mod Podge. Set it aside to dry.