Long-haired cats usually need frequent(daily) brushing to prevent matted coats. When you find small mats, they can often be teased apart with a comb. Larger mats can be cut away.
You can buy a special cat brush and try to brush your cats fur. Though be really careful that the cat doesn't harm you from the sudden new thing that you are doing to it.
You can go to your local pet store and buy a conditioner for your cat to help with matting. You can also groom your cat yourself everyday to prevent matting as well.
