Mac OS X Server includes the Workgroup Manager, a tool for user management, which allows you to create and manage users, groups, computers and computer accounts and groups. You can also use it on the "About" screen access, an advanced feature that allows a first processing of Open Directory entries.
Workgroup Manager works closely coupled with a directory domain. Directory domains databases are comparable, but specifically tailored for storing account information and user privileges for certain activities.
Information about using the Workgroup Manager can be found in several documents:
The manual user management is explained how to use Workgroup Manager to manage accounts and settings. This manual also contains information about how accounts will be imported and exported.
The Open Directory administration guide explains how to use the window "Information" section.