On the top menu, go to "Home" and then to "Join us!". 

The next page you see will explain the differences between a free and upgraded membership. You do not have to make this choice yet until after you are registered. By default, your account will be a free one and you will not be charged anything, nor will we ask you for bank account information. If you wish, you can upgrade your account at any time later on, and if you don't want to renew your upgrade subscription, your account will automatically revert to a free one. If you choose for a free account, it will remain free indefinitely.

To become a member, you need to fill out the registration form and submit it. Then, you will be sent an e-mail with an "activation link", on which you need to click to activate your account. Once you have done this, you can login on the website. An intro tour will help you set up your account and profile further.