Based on the real world Indigo EFB background image. 
You will find two version to choose from: Colour and black edition


To Install
1. Download and extract.
2. Run your sim and launch Fenix A320, ensure Fenix app is running.
3. Open your browser and use this link http://localhost:8083/
4. Go to settings and you should see the option to select a new wallpaper.

https://kb.fenixsim.com/change-efb-image-web-mcdu outlines the steps to install a new EFB background.