Here's a rundown of how this feature works, exemplified by the real-life case of our little MtG community in Cluj-Napoca.
Laura and Sergiu are responsible for planning and setting up our bi-weekly Magic the Gathering events. They create a new community here on deckbox, and fill in the name, a short description, and location information: GameFlux. There! Ready to invite some users!
Then, on the event page they create the upcoming events. Members can now - upon visiting an event's page - confirm their presence and see who else is coming. The upcoming events are also shown on the profile page of all community members, as well as on the profiles of users from the same city as the community.
Finally, as our community did not have a forum before, only a mailing list, we can set up a subforum here, where the members can discuss whatever Magic communities discuss 
We hope that really soon the community admins will be able - upon an event's completion - to specify the top 8 standings and the winning decks, so people can see the winners and their decklists. Those decks will be rate-able, and commentable.
For now, a big, big THANK YOU to Laura for this great feature! And let's post some feedback and feature requests for these communities, so she has her share of bugs and enhancements 