You can drag it to the Favorites pane or right click and add it to Favorites.
If the Unread folder is not listed under Search Folders, right click on the Search Folder then create a new search folder.
So my Search Folder is called Unread Inbox and combines all of the “new” items into one view.
Then I can quickly scan for important messages, and optionally, use Control-A to mark all messages and then use “Mark as Read.” In Outlook 2000 and later, after you receive new mail, the Folder List opens to show any folders in the hierarchy that have new, unread items.
Other than that, Outlook does not provide much help in locating unread items.
Using the Instant Search method, you would type read:no in the search field and click the Search All Mail Items link.
This search will include unread messages from all folders in your profile but the results are limited to 200 messages in the initial results, which is fine if you are good at marking your email read, otherwise you need to click again to view all unread messages.