How to add User Accounts for users to administer their personal accounts

In many apps, you will want customers to create and manage their own accounts. How do you go about it?

I am investigating how to do this, but in case someone out there knows better, please edit and share your knowledge. I am just new to Ruby and to Rails.

# == Default Namespace
#
# Set the default namespace each administration resource
# will be added to. 
#
# eg: 
#   config.default_namespace = :hello_world
#
# This will create resources in the HelloWorld module and
# will namespace routes to /hello_world/*
#
# To set no namespace by default, use:
#   config.default_namespace = false
config.default_namespace = :admin

Looking at this code am tempted to believe you can add another namespace like follows:-

# To set no namespace by default, use:
#   config.default_namespace = false
config.default_namespace = :admin
config.default_namespace = :account

#OR config.default_namespace = :admin, :account