I'm pretty sure this is not designed to be a virtual table top like you seem to want. Instead it's supposed to be a map editor that you can use to create a map for use with a proper VTT like Roll20 or Foundry. Both of those programs solve your issues: multi player, fog of war/line of sight and dynamic lighting, import custom images for backgrounds.
The export current map as an image file button is in the top left next to the save buttons.