Nokia Glance Background beta has been released for Nokia Lumia Windows Phone 8 smartphones. The app allows users to customize their glance screen on your Lumia WP8 smartphone with a personalized background image. Glance Background lets you set any of your own or preloaded images as a background for Glance screen for your Lumia device.You can download the app directly on your device through the Windows Phone Store or by using the following link:
Press the Search 
button on your Windows Phone, tap Vision 
and then scan the following barcode by pointing your device camera toward it
button on your Windows Phone, tap Vision and then scan the following barcode by pointing your device camera toward it 
Glance Background for Windows Phone has the following features:
- Single or multiple (up to 4 ) images selectable for your glance background
- Choose from several high-quality preloaded images or your own
- Create new backgrounds from your own pictures
- Optimize your images with a simple editor (preset effects, colorize, zoom)
- Save modified images for later use
The app require latest Amber update with General Distribution Release 2 (GDR2) and will work on the Nokia Lumia 1020, Lumia 928, Lumia 925, Lumia 920, Lumia 820, Lumia 720, and Lumia 620. However it won’t work on the Lumia 625 or Lumia 520 as they don’t support the Glance screen feature.
Keep in mind that this is a beta application, so be sure to report any issues you face on Nokia Beta labs.