There are a two ways to add a new user or Provider from the Configure menu, and both of which require the appropriate security access:
Configure > Add User / Provider. This option is used especially when the new user you wish to add is also a provider, as it enables you to set up appointment books and rosters at the same time as you are adding the user record.
Configure > User Settings and click the +1 button to open the Add User window:
See the User Settings section for details of field options.