How do I change my desktop background?
To change your desktop background open the settings app. First click the windows key on your laptop () then click on settings. Click the "Personalization" tile, and then click background. In the page that shows up, you will be able to select between a photo, colour or slideshow as your background.
When you're ready, click on the "Browse" button to find either a folder (for slideshows) or a photo.
Select the "Choose this ..." button, and your desktop background will change to the photo(s) you have selected. You can also adjust other settings in the same page to alter how your background will look.
Choose a Fit
Under "Choose a fit" you can select how Windows should display your image. "Fill" mode will not change the aspect ratio (which would stretch the image), and instead zooms in to the image until the whole image covers the screen.
"Fit" will display the whole image without changing the aspect ratio as large as it can until one of the edges touches the edge of your screen. Any extra space will replaced with a background colour which you can set. Stretch will change the aspect ratio/proportions of the image until the whole image fits the screen (without showing any background colour).
"Tile" will display your image at it's normal size, and will repeat the image if it can't fully cover the screen. Center will display your image at it's normal size (centered in the middle of the screen). Anywhere not covered by image will display your chosen background colour. "Span" is similar to fill, except if you have multiple monitors connected, will try expand the background so it forms one continuous background on all your monitors.