Directly within the app, with the Facebook or Google connect buttons after the first launch. It is the only way to sign up or login. Don't worry about your data privacy though, no user data is shared with third parties and only your basic data is retrieved by the app. Facebook and Google are only used to speed up the registration process and prevent bad behaviors.
(you might notice a 'v1 users" button, it is reserved for the users of the v1 who have registered with email. It will be discontinued soon)