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

[Schlaegel]

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.