Deanoe

Hi, I've just installed Bandits no clutter 200gb hyperspin image to my 2017 nvidia shield, all is working good but I'm confused as to how I add a new system ( Atari 2600 ) as there are no tutorials that I can find. I have 900 roms placed within a folder called Atari 2600/roms, how do I get the system to show in the platform list? How do you download the artwork/music/bezels to the Nvidia shield? How do I set up a default emulator for a system? If someone could tell me step by step process that would be much appreciated Thanks