Screensavers were originally used to prevent monitor "burn in" when older CRT monitors are used. Nowadays, most people will have their PC, laptop or tablet set to go into sleep mode when it hasn't been used for a while. However if you'd like to set a screensaver or make it so that your PC automatically locks itself after a set amount of time, please follow the steps below.
First, right-click the desktop and click Personalise. You can alternatively go to Settings > Personalisation:
Now click Lock Screen from the left menu, then scroll to the bottom of the main window and click Screen Saver Settings:
You'll now be presented with the Screen Saver options menu where you can choose your preferences. If you'd like to force a user to re-enter their password once the PC has been unattended for some time, make sure you check the "on resume, display log-on screen" option.
First, right-click the desktop and click Personalise. You can alternatively go to Settings > Personalisation: