Windows Phone 8.1 update brings a lot of features and enhancements to your smartphone, one of these features is the new Start background, which is a new way to personalize the Start screen with a photo instead of a simple solid color. The Start background is available on all devices supporting the new Windows Phone 8.1 update and here is how you can configure it.
1. From the new notification center tap ALL SETTINGS.
2. Then tap start + theme.
3. Locate the choose photo button.
4. Pick a picture from your albums on Facebook, camera or backgrounds folder, or OneDrive — you name it.
5. Crop image as necessary and tap the check icon to confirm your new settings.
Voila! That’s all there is to it. As you head back to the Start screen the Live Tiles transform to show part of the photo you selected on each Tile.
Keep in mind that not all apps Live Tiles support the new Start background feature as this is something developers has to enable on each app — Hopefully apps will update to add the new feature.