Hello! I'm not sure if this is exactly what you're asking, but as a somewhat seasoned regular in the RP section, I'd love to let you know what happens.
First, any new RP ideas are posted in the New RPG Ideas subforum. It is aptly named. In these threads, the GM (game master, I guess) uses the first post (or two) to explain the premise of their RP. Then, people post their bios, usually using a pre-made template provided by the GM. Some RPs are closed to new applicants or invitation only, so look out for that, usually at the top of the first post, and don't post if they are. If you absolutely have to be in said RP, you can PM the GM.
So, now you've posted your bio and you're in an RP. One of two things can happen... If it's a new RP, you have to wait until the GM PMs a Mod and gets the thread started in the Main Roleplay subforum. Usually, the GM posts first to get the story going. If you've applied to an RP already in progress, you can post anytime, but it's usually good "etiquette" to read the whole thread start to finish or at least get the important stuff from another RPer.
On CAA, here are how most of the RPGs work: They are not real time. People post when they find time and some RPs move faster than others depending on who is in the RP. A majority of the posts are written in prose, and so RPing here on CAA is a lot like writing one big story with a lot of other people. There's basic rules, usually outlined in every GM's first post, but generally there is no godmoding (If you don't know what this is, my personal favorite godmoding explanation site is
here). You can check out CAA's official rules for every RP in the Main Roleplay section under the stickied thread titled: "How to get you RP approved." Depending on who you're RPing with, some people may prefer that you always type in full sentences, and not use other writing styles such as:
Character: Hello. (thinks) This is weird
"Hello." *Character moves across the room* *thinks: this is weird*
[color="Red"]Hello.[/color] [color="Green"]Character walked across the room.[/color] [color="DarkSlateBlue"]This is weird.[/color]
Or, you know, any other combination... But in other RPs, that's fine. You kinda have to feel your way with the whole acceptable grammar thing.
Anyways, that's pretty much the gist of it. I hope that made sense, and if you like RPing I'd love to see you around the boards!
