Hello, Hmmm! I'll bombard you with some random information!
This is a fansite of Brandon Sanderson's works, as you should hopefully know.
Most of the forums' purposes can be determined by exploring, and most are self-explanatory. However, if you haven't read all the Cosmere works yet (adult fiction like Mistborn, Way of Kings, Elantris, etc.) I'd stay away from the Cosmere Theories section. Major spoilers there.
There's a reputation system that works on upvotes/downvotes on posts. Those are the red and green arrows on the corners of every post. Upvotes for if a post was funny/awesome/helpful/whatever, downvotes if it was offensive or very, very bad in some way. Your total reputation is the number underneath your picture on the side in the box. (That wasn't confusing at all.) If you're at zero rep, like you are now, you're a "Spren." The names don't really do anything except provide amusement. Rep doesn't mean anything, but it makes you feel accomplished.
Try not to double post, as a general warning.
If you've read Mistborn, you probably understand what I mean when I say that if anyone offers you a cookie it's spiked. If you don't, just know that it's not alcohol. It's literal spikes.
Explore! Have fun! I'd give you an introductory upvote, but I've hit my upvote quota for today. Anyway, go thee forth and do stuff!