Hi
Since my previous posts, a new extension became available for importing users. See
extensions.joomla.org/component/option,com_mtree/task,viewlink/link_id,2613/Itemid,35/
To be clear, CB syncronises users with Joomla's main user table. Every time someone registers using CB, they get added to the Joomla list as well.
If you use the importer, it will probably add the users to the Joomla table as well.
If not, CB comes with a tool that very simply and quickly syncronises the tables, so you don't need to worry.
Regards
Brendon