The Picture option lets you choose one of your photos for your background, and the Slideshow lets you choose a folder that will cycle through a collection of your photos. You have three options for the lock screen background: Picture, Slideshow or Windows Spotlight.
Here's a handful of tips for customizing the Windows 10 lock screen. You can add your own photos for its background or let Windows add rotating images. It can be set up to show app notifications, calendar events and the date and time. The Windows 10 ( $148 at Amazon) lock screen can be more than just a password-entry screen. It's something you stare at each time you sit down in front of your PC, but I doubt you even see it as you quickly type in your password and unlock windows.