Watch: birthdate and parent permission
The opening of the individual registration video: birthdate, and permission when you are under 13.
This is the opening section of Registering as an Individual Website.
You enter a birthdate on the Register tab. If you are younger than 13, the form asks for a parent or guardian. They receive an email that you want an account. If they do not have email, a teacher can receive it and print it. You finish the account only after they say yes.
The written steps are in Register an individual website.