From a Home screen, navigate: Apps > Settings > Security.
Tap Screen lock.
If presented with "This device does not have a Google account associated with it. If you forget your PIN, it cannot be sent to you and a factory reset will have to be performed to recover the device.", tap Add Google account now to setup the account before proceeding. To proceed without setting up a Google account, tap Continue.
If presented, enter the current PIN/password/pattern.
Tap Face Unlock.
Tap Set it up.
Position face within the provided area.
Hold still for several seconds to allow image capture.
From the 'Choose backup' lock screen, select one of the following options:
If presented, tap Next.
Draw an unlock pattern (connecting at least 4 dots) then tap Continue.
Re-draw your pattern then tap Confirm.
If presented, tap OK.
Enter a numeric PIN (at least 4 digits) then tap Continue.