In the starting dialog you can either log in (or ask for a forgotten password) or to register as a new user if you come to the WAusers site for the first time.
New users are asked for login name, password, e-mail address and other contact information. Providing e-mail address is optional, it serves currently only for the purpose of resetting forgotten user's password (it's not possible to reset password for a user without e-mail address). In future, it may be used also for sending notices regarding the WAusers site (such as maintenance notices). Other contact information is completely optional, it is displayed to users participating on the same WAassistant projects.