Kill 1 Feral.
You encounter your first Feral while traversing the Rose Heights Cemetary. You will see a man digging up a grave, drop down and you will get a cutscene, the Feral will then attack.
Ferals can be very annoying, they are fast and can pin you down with their lunge attack and deal some heavy damage.
The weapon of choice for Ferals is the knife. Do the A,A,A,X combo to pin it down and just repeat, occasionally if may get in an attack after the X attack, so make sure and be ready to dodge.