At any given time, there's only one unlocked Question Thread, currently it's 12. That's the thread we use for discussion and planning.
The RPG itself works pretty easily. In the Question thread, we plan out what will happen, and make a lot of jokes, Then we make the plans happen in the City threads by writing for our characters.
It's best to introduce your character in the Question thread so that the rest of the players can vet it, making sure they aren't too Op and such.
For a more in depth explanation, check out What is Free form Roleplaying and Rules and Etiquette.
EDIT: Ninja'd by Twi. Of course I Was.