You can search for iCM groups and users from the top title bar or the search action in the left-hand actions panel.
Your search query is matched against the following properties.
Use the checkboxes to restrict the results to users, groups, or both.
Use an asterisk to perform wildcard searches.
Searching on * will return all groups and users that match your filters.
You can also use an asterisk to perform stemming. So Fred* would return Fred and Freddie, but not Alfred. Conversely *fred would only return Fred and Alfred.