How do you lock your screen for iCloud backup?

Lock the screen means putting the device to sleep. If you have an iPhone 5s, press the button on the top right corner of the device to lock the screen. When the phone is plugged into charge, connected to WiFi and goes to sleep, automatic iCloud backups can take place. You can create a manual backup by going to Settings>Your Name>iCloud>Apps using iCloud>iCloud Backup>On>Backup Now.