AA is simply a place for all groups/teams/orgainzations to come together and discuss games/guns/gear/events.
Hosting a game is easy, getting people to attend your game is hard.
Get a date, a place, a time, construct of who is running it, a timetable of events (start, end, objectives, outcomes), a story, team identification (who is on what side and how do you know), historical background is good but not nessisary. make sure rules are stated and enforced.
Post it up and ask people to attend. be careful not to put it on dates of other games or national events.