To search for users and groups, use the Search Users and Groups dialog box:
When adding users to groups.
When connecting a domain user or group.
When adding privilege holders.

Select subject type, arrangement, and enter user names or groups to search for subjects.
Select subject type and arrangement
Enter users and groups by names
See also:
Creating User Accounts and Working with Them | Creating User Groups and Working with Them | Viewing User and Group Objects