Use The Lock Screen 
To protect personal information, you can adjust your phone's lock settings:
- From the Home or All Apps screen, touch the Settings icon
. - Scroll down and touch Security.
- Touch Screen lock.
- Touch the type of lock you'd like to use.
.After you set a lock here, a lock screen displays whenever your screen wakes up, requesting the pattern, PIN, or other specified key.
While the screen is locked, you can respond to incoming calls in three ways. Touch the white phone icon and slide over one of these icons:
