If only children were as easy to potty train as is it to train a cat to use her litter box. Cats are fastidious creatures by nature and go to great lengths to keep themselves clean. They also tend to bury their waste, making them perfect candidates for using the litter box. Most people only have to show their cat or kitten where the box is and training is done, but here are some tips on how to help training a cat to use a litter box, just in case.
Start with a size appropriate litter box and add clean, fresh litter. Place you cat or kitten in the box. You may want to use the tips of your figures to scratch the surface of the litter, and some cat owners will gently use their cat's front paws to scratch at the surface. For cats, this is a pretty clear signal that this is where bathroom breaks are. Let your cat figure out how to get out of the box alone; it's usually just a little jump, and how to leave the area.
If your cat doesn't have it figured out immediately and goes outside of the box, pick up the waste and place it in the box. Gently pick your cat up and let her smell her waste in the box. Never yell or rub her face in the waste. This will only scare her. She should be encouraged to use the box if you show her where it is and encourage her with her own scent.
If she's still not doing it right, you can practice confinement in the litter box room with fresh food and water for her. Try different litters too. Your cat may not like the litter you chose for her. A cat will usually get the message pretty quick, and if she doesn't, she may be suffering from a medical condition and your vet might be able to help resolve litter box avoidance.