well, you've posted at the right time then. In a PbP site, we generally play just like in the meat world, just it takes longer, what would normally take 20 minutes, might take a week, or it could take a single post depending on the gm. What you first need to do is make a character, and find a run that has an opening.
The coolest advantage to PbP, is that you get time to post, you don't have to rely on improvisation on the spot, you do have a bit of time to think, plan, and then react. I like it because it allows you to think about your character more.