From a Home screen, tap Apps (located in the lower right).
From the Apps tab, tap Settings.
From the Personal section, tap Lock screen.
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., select 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.