One of the Masons on this board can probably give you a better answer than I can (my husband is a Mason) - but as I understand it, you should find a nearby lodge, get to know some of the members, and express your interest in joining. It's a little like rush, except that you have to explicitly ask them "How do I join?" for the process to start (rather than them inviting you / offering you a bid).
The three basic qualifications are that you must be male, at least 21 (which you've just met), and believe in some form of God.
Good luck
