This post will show you how to change the wallpaper or background image of your PC desktop or lock screen. The desktop background image or wallpaper is the background image on the desktop area of the PC while the lock screen background image appears when the screen is locked with a password.
To set a desktop wallpaper, right-click on your desktop and click on your desktop and select ‘Personalize’

Under ‘Background’ click on the drop down arrow for options, there are three options for background: picture, solid color and slideshow. If you select picture, you can choose a picture installed by the Windows or from your gallery, for solid color, you’ll need a select a certain color, for slideshow you have to select at least 2 pictures from your gallery to create a slideshow – you can set timer on when the picture changes and other settings like shuffle and ‘allow slide show when on battery power’

Under ‘choose a fit’ select how you want the background to be presented on the screen by clicking on the drop-down arrow to select the options. The options available are: fill, fit, stretch, tile, center and span.
To set lock-screen background or wallpaper, in the same window, click on ‘lock screen’
There are three background options: windows spotlight, picture and slideshow. If you choose windows spotlight, windows will display images from the windows library, for picture and slideshow, follow the steps for background.

Is it possible to include 2 background pictures at the same time ?
No, at the moment except you use a photo editing app the edit the pictures and the upload as background