Use photos as your screen saver on Mac

You can use personal photos as a screen saver to hide the desktop when you’re away from your Mac.

On your Mac, choose Apple menu > System Settings, then click Screen Saver in the sidebar. (You may need to scroll down.)
Open Screen Saver settings for me
Scroll down to Other, then click Photos.
Click Options at the top of the window.
Click the pop-up menu, then choose Photo Library.
Choose a set of photos on the left, then click Choose.
Click OK.