lock my screen
How do I make sure my screen is locked in order to do the iCloud back up
iPhone 5s, iOS 11.3
Press the sleep/wake button on the side of the phone or just wait for it to lock automatically based on the time you have set in Settings > Display & Brightness > Auto-Lock.
Note that the screen does not need to be locked if you are doing a manual backup to iCloud (i.e., Settings > [username] > iCloud > iCloud Backup > Back Up Now)