How do you roast coffee beans?

One of the methods that I heard of, and currently use, is a popcorn popper. You must use the hot air, side blowing, type popcorn poppers. By side blowing, I mean the type that blows air in the chamber from the side not the bottom. Using a bottom blowing popper will result in burnt beans at the bottom and raw beans on the top.

Another method is to do it in the microwave on a very low setting.

Roasting times vary depending on the strength of the machine you are using, as well as how moist the seeds are. So keep your eye on them while roasting, and experience will allow you to know when they are roasted to your liking.