Hi!

From someone who has joined them recently: there are some informations down, at the very end of their front page. The letters are very small, but you should be able to notice it. It says:

For Contributors

Sell Content
Profile & Portfolio
Upload
History
Earnings
Referral
Tax Center

Also, when it comes to joining them, you have to agree to their terms. When you click on these terms, you can read it, there's lots of informations in it.

Hope this helps!