A .22 rifle is a great beginner's gun. There is almost no kick, the ammunition is very inexpensive, and he can learn the basics before moving up to a more powerful gun.)
Go to a nearby gun shop and see if they can tell you where a range is. You can also check out www.wheretoshoot.org for a range in your area. I would also recommend signing your son up for a youth firearms safety program. (It would be a good idea for you to take a safety class, too, so you're comfortable with his shooting.)
As far as equipment goes, he will need ear plugs or earmuffs, safety glasses, and a gun cleaning kit. All of these are available from either a gun shop or a department store like Wal-Mart.
I hope your son enjoys shooting. It's a fun pastime, teaches concentration and patience, and is a much better way to spend an afternoon than playing video games.