If you want to make your own specially branded version, such as for a particular event, then to change the default desktop backgrounds edit the images within *img/backgrounds* and to change the available avatars and desktop icons edit the images within *img/avatars*. Re-create disk images using the instructions shown previously.
If you need particular /dconf/ commands to alter desktop appearance or behavior then see the function /mesh_client_startup_applications/ within *src/freedombone-image-customise*.