If you're just starting out performing magic tricks, making a red sponge ball disappear in your hand is a simple trick to learn and fun to perform. One of the benefits of the disappearing small ball trick is that you can practice it almost anywhere.
Make a partial fist with your left hand, leaving space between your fingers and palm. It may help to imagine you are holding a hot dog in your fist that is pointing down toward the floor and upward to the ceiling.
Hold your left hand in front of you and place the red sponge ball on the top of your fist.
Use your right thumb to push the sponge ball into the cavity created by your partial fist. However, instead of pushing in the ball entirely, use this motion to pinch the ball between your right thumb and index finger against the palm.
Pull your right thumb away, which is now cradling the ball inside your right palm. Push your right index finger and middle finger into your partial fist to give the impression of stuffing the ball inside your left fist.
Open your, now empty, left hand with a grand gesture to reveal that the ball has disappeared. After a suitable pause, reveal the sponge ball in your right hand.
Practice hiding the red ball with the fingers of your right hand. Perform the trick in front of mirror to ensure that anyone standing in front of you will not be able to see the exchange from left palm to right hand take place.
Always perform magic tricks like this with your spectators in front of you. If someone asks to stand to the side or behind you, just say, "I'll give you the best seat in the house--right in front of me." Practice magic tricks in front of a confidant who can offer constructive feedback about your technique or presentation skills.