From the FAQ

"My account has surpassed the minimum payout limit. How do I request for payment?"

"No request is necessary. if you are eligible, we will pay you according to the payment method you have selected in your profile. We normally process payments by the 3rd working day of every month. Payments should reach you latest in 2 weeks time for Paypal and MoneyBookers. For photographers who have opted to receive payments cia check, please allow up to a month for the check to reach you."

However, if you look at your "My Earnings" page you may see a notice like this....

Note: Click here to submit your ID/Passport for payment verification. The ID/Passport requirement only serves as a verification purpose in order to establish the authenticity of each account holder. All personal details will remain undisclosed.

Apparently if you haven't submitted your identification they won't pay.

Also, if you haven't already, you should make sure the "Preferred payment limit" is set below your current earnings.