[Zope] How to implement a "join", can't add users via zpt or py

I need to let anonymous users join and create a username for themselves. I have scoured the archives and websites and not found anything that I can get to work. I am using zope 2.5.1. I have tried using both zpt and py. I tried container.acl_users.userFolderAddUser(name='viascript',password='password',roles=['User']) which gives an authentication error. and container.acl_users._addUser('viascript','password','password',['User'],0) which gives an invalid attribute name because it starts with "_" error Please help me here. I'm sure it must be an obvious answer for someone who has more experience than me.