Click on the "+" in the footer menu, then again on the "Favorites" tile. This will produce a list of workouts you've marked as "Favorite". You can then easily perform various actions for each workout by clicking on the "+" icon next to each workout.
To a Favorite workout, head to the explore tab and select workouts.
Select the "WODs" filter.
Select and apply the "Favorites" filter.
This will produce a list of each of the workouts you've marked as "Favorite".