Click "Log In / Register" at the top right and switch to the registration form.
Enter your email address and click "Send code". The code is delivered by email and stays valid for 5 minutes. If you do not receive it, you can resend it after 60 seconds.
Enter the code and a password (at least 8 characters with both letters and digits) and submit. You are signed in automatically once registration succeeds.
If you forget your password, choose "Forgot password" on the login page and reset it with an email code. All previous sessions are invalidated immediately, so please sign in again with your new password.