Hello Miku-friend,
To answer your questions, this Guild is not unlike any other forum RP you might have been a part of prior. Where you are not is obviously the OoC where you just chat with the player themselves about this and that. Below I will give you a couple links to help you get started:
Here is where you find your profile format. Fill out the Persona-User format and I'll post it in the Normal Citizens section of the Profile Subforum when you're done. It's a link to the Characters and Profile Skeleton forum on the front page.
Here are the Rules and Announcements, which will give you a quick guide to the rules and let you know what time it is in the RP and what's going on at any given time. It's also on the front page above this forum.
Here is the FAQ, where any general questions you have might already be answered for you. If there's something confusing you, good chance you can find an answer to it here. It is on the front page.
Finally,
Here is the Inaba Subforum, where most of the RP is currently taking place. All of the different forums you see are places where you can post your character doing whatever different things you might want them to do. When you want to go to a different location, just switch forums and post in the new one.
I'm assuming you are familiar with RP at least, so that part should come easy. The rest...you can figure out as you move along. There's no need to cram all the information in here into your brain on Day 1, anyway. XD