Well, the rules are not all written and fixed, but more or less are the following:
-You can control your character. The other's characters are not completly in your control but, of course, if you interact with another person, you have to write his/her reaction and, perhaps, make him/her do things. I don't know if I expressed myself too well...
-There's not a predeterminate order, although a general rule is to wait until writting again after your post. If no one replies it, perhaps you can add some action to cheer people up to add more things.
Wish I was clear enough