A Favorite Search is simply a Saved Search that can be monitored for New/Updated listings from your Home tab.
To create a new Favorite Search use the following steps,
Step 1: First start any Search, Click on Search Tab
Step 2: Select Criteria and Click Results
Step 3: Save Search, Click Save
Step 4: Choose and Click, (Both New Saved Search or New Auto Email will allow you enable search as a Favorite Search)