First time you get to this page you will have to check your mailbox and you should get an email where you have to confirm your subscription.
If you don't receive that email, check your spam folder, and add firstname.lastname@example.org to your contacts.
When you have confirmed your subscription you will get to this page again.
Then finally you will receive a welcome email that will be titled "Thanks for joining us".
When you have received this welcome email your subscription is confirmed.
In this welcome email at the bottom of the email you have links to update your preferences or unsubscribe from this email list.