Being stroked is pleasurable for your cat, so it isn't difficult to teach them to like being brushed. By brushing your cat to remove excess hair, you will prevent your cat from getting fur balls in their throat. Brushing your cat also helps get rid of knots or prickles they will have got from exploring outside, as well as letting you regularly check on them health-wise.
Choose a time when kitty is feeling a bit sleepy and wants to curl up on your warm lap. Have the brush handy so you don't have to disturb him to get it. If he hasn't seen the brush before, hold it near his face so he can sniff it all over if he wants. In this way he will understand that it won't hurt him and so he won't be frightened of it. In fact, it's a good idea to rub your own hands along the handle of the brush so he can detect your scent on it. If he's used to you, he will be reassured that this strange tool is to be trusted.
When he's happy and has accepted the brush, you can begin by brushing him gently and slowly. Don't brush against the way the fur lays, brush with it. Should he use his paws to try and play with it, put it away. You don't want him to learn that it's something to be played with, but that it's for brushing only.
As soon as kitty has quieted down, start to brush him again. Start at about ear level and work backwards with a long, fluid movement. Never try to brush his face, or you might damage his delicate eyes and whiskers. Brushing the tangles out of badly matted hair can cause pain, so be careful to do it gently. If kitty expects pain every time he sees the brush, he won't be amenable to the process.
It sometimes useful to have a few different brushes for your kitty. Bigger, stiffer brushes are good for their back and sides, while for their more delicate areas, such as the stomach and tail, a softer and smaller brush can make things easier.