How can I invite my Facebook friends to Stack Overflow? Is it possible?
Give them a link to http://www.stackoverflow.com/, and tell them to visit that site and click the "Ask Question" button in the top right-hand corner.
That will walk them through the process of creating an account to ask a question. Since they already have a Facebook account, it is quite easy: all they have to do is click "log in with facebook" and enter their login details.