I would say tha you're going to need to learn some sort of scripting language like php for starters. Then I suggest sitting down with a piece of paper and brainstorming all the possible thing you would like to be able to do in a game. Then you'l have to program it using your language of choice and database (mySQL). I would create it in modules that are called and run separately for each different action.
Sounds like a lot of work. Probably is. Don't mean to scare you.
I would also start by trying to get a team together to help you. It would take probably 1000's of man hours to do. So if you get a team together, you'd probably have a better time doing it as it would actually get finished.
Good luck. :wave: