As of the opCharts 3.2.6 update you can now upload custom Map Icons and Backgrounds using the web interface.
To do this, navigate to menu -> System -> Files as shown below.
From here you can select the Resource type icon, or maps_background. Give the resource a name, then click "Browse" to navigate to the desired file for the icon or background. Once the file is selected click Upload.
Once the files are uploaded you can view them in the uploaded files menu at the bottom of the Files screen.
