New registrations should already send you an email. Please ensure in CB configuration on moderator tab you've set moderator emails to be sent. Please then check your user in User Management to ensure they're set to receive emails.

Alternatively you could use incubator project CB Emails and configure a custom (substitution supported) email to send after profile update or after registration.

I can't get this working... is there a tutorial about this?

Please provide a screenshot (TO address blanked out) of how you've the email trigger structured so can better advise what needs to be adjusted. CB Emails uses jQuery to guide you through the configuration, simply follow the inputs as they become unlocked (non-gray). Please also ensure to review carefully the information to the right next to each input. There are no tutorials and documentation for incubator projects, sorry.

There's a known bug that results in only 1 user receiving the new user registration moderation email. This is not an issue if you're the only person configured to receive moderator emails. Otherwise please use CB Emails to send your self a custom email after a user registers.