1. Navigate to the Display tab
2. Click the checkbox next to Backgrounds Folder
3. Select the folder containing your new backgrounds or replace the backgrounds in the default folder using the exact file name:
C:\Program Files (x86)\PhotoBoothSolutions\SocialBooth\Assets\Backgrounds\
All backgrounds should be designed in 1920x1080 resolution. If your monitor resolution is smaller you will not be able to see the outside of the background.