My first piece of advice would be to head to the "Out of Character (BA Help Thread)", that's what it's for, because as soon as one of the mods sees this, that's what they'll say, right before they lock it.
To answer your question, this is online story telling at its most fun!

You create a character, (see the character approval part of the Battle Arena for more details, specifically the Character Approval Policy). Then, you can either start fighting battles, or you can visit "The Dome- Training Ground" (where I happen to be a teacher) where you'll get tips and instruction on RPGing.
If you have more questions, head to the Out of Character Thread, or you can even PM them to me personally. Always happy to help out a newbie!
Hope to see you around!
