This is what I would do:
1) Secure his computer. If he's using windows make a non-admin account for him, setup automatic updates and an updated anti-virus program.
2) Install Chrome or Firefox and make it his default browser.
3) Setup a Gmail or Yahoo email account for him.
4) Setup his desktop, quick launch and other shortcuts so that it's clear how to get to the internet.
5) Teach him to use his email account.
6) Set his home page to google, and teach him to search.
7) Show him how to use able2know so he can ask us for help when he needs it.
As long as the computer is secure and he knows not to give out his information to scammers and phishers, there's really no harm in learning as you go.