The drop-down menu (at the top right corner) in the student area has a Settings item.

After you have created your account, you are encouraged to use this to fill in your contact information and other details.

The menu also has a item for changing your password. If you have forgotten your password, then the login page has a link that you can use.

The "Forgotten Password" mechanism is similar to the one used when creating your account. A confirmation email is sent to your email address, and you need to click on the link in that message to complete the procedure. The confirmation email has a temporary password, which you should use to login in. After logging in, you should use the "Change Password" menu item in the dropdown menu to change your password.