You'll find Search Folders in the Navigation Pane.
Once you create a Search Folder, you can find it in the Navigation Pane. You'll see a folder there called Search Folders, which contains all the groups of search results you've created, as well as three default Search Folders: For Follow Up, Large Mail, and Unread Mail.
Because Outlook keeps Search Folders up to date, you simply click a folder to see its most recent search results.
Note If you use Archive Folders or Personal Folders, be aware that each of these locations will have its own set of Search Folders. That is, Search Folders for your Mailbox work only in your Mailbox, Search Folders for Archive Folders work only in Archive Folders, and so on.