I think I was 16 when I "tried". The amount of work that needs to go into this project far exceeds what I'm willing to devote, especially since I'm not an artist.
Josiah if you don't have a lot of experience in building large scale applications involving a Server I would highly recommend looking into another kind of game and seek experience first. If your heart is set on developing a MMO you should check out the open source project from Mozilla
http://browserquest.mozilla.org/. This is going to be one of the simplest functioning MMOs you find being it's almost entirely developed in JavaScript.