Once you've found a benefit you want to save as a favorite, enter it and click on the heart icon on the right.

Once you have marked it as a favorite, you can see the list of benefits saved from the My transactions link found in your avatar in the header.
Once on the My Transactions page you can view your benefits saved as Favorites.

From your cell phone, when you enter the benefit you mark the heart found in the header and it will be saved in your Favorites.

To see all your benefits saved as favorites, you must go to the My Account icon and go to the tab with the Favorites list.