By clicking on thetab in the top main menu a navigation tree with all registered members and there group membership is displayed in the left side of the screen. By clicking you can select the desired member.
Additionally you have the choice to do a full text search:
Enter the name of the member you are looking for in the search field in the top left corner.
Confirm by clicking on the arrow adjacent to the field. A list will be generated with all according members and documents.