The easiest way to teach a cat is based on its habits. For example, all cats can get up on their hind legs. You can develop this skill. Take a piece of food in your hand and lift up over the head of a cat. First, make sure the food is not very high so that the cat could easily get a treat. Then slowly lift that cloth up. The cat will follow that piece with it's back legs.
It is very easy to train a cat to bring a ball. First, tie a rope to the toy and fumble the ball on the floor. When the cat will grab it with it's teeth and paws, slowly pick up a toy and treat humming to yourself. You should say "give me the ball" and repeat it several times. This might take some time to master so be sure that you are patient. Keep on trying this method until your cat gets the hang of it and responds accordingly.
Most cats are very fast learners. Sit with your pet and take the front paw in your hand. If the cat remains calm, praise it by giving a pat on the head. It will encourage the animal to adapt. Training a cat can sometimes be difficult especially if it is aggressive early in life. Remember that you are in charge and that the cat should understand this. Do not let your cat get a way with biting and scratching as this will make the cat think that it can get away with anything in the house. Be sure that you are firm and keep your voice in a serious tone when trying to discipline your cat. After a few times your cat will understand that you do not like it when it bites or scratches and will give up this habit altogether.