Double-click a tag.
Click the box next to one or more tags.
Drag one or more tags from the Keyword Tags palette to the find bar near the top of the Photo Browser.
The application finds all photos that have any of those keyword tags attached. If you select a keyword tag category or subcategory that itself has nested subcategories, the application displays all photos in the hierarchy. For example, if you have a Wedding subcategory that contains the keyword tags Bride and Groom; and you select the Wedding subcategory, all photos tagged Bride or Groom are displayed.