Adding ROMs

Adding ROMs is the easiest venture by far. Just go to the various ROM downloading sites like this one, find the ROMs you want and download them  into their respected folders in the "/home/pi/roms/" directory in the file manager on Raspbian. Either download on your PC, MAC or Linux machine and copy over to your Raspberry Pi using a USB, or use the  Midori or Chrome browser ("sudo apt-get chromium") and download straight onto the Pi. Make sure you put the right ROMs in the right emulators ROMs folder or the emulator will not see the game. You can also follow here for more ROM adding options.

After adding your ROMs, reboot into PiMAME and map your joystick. Select the emulator you wish to use, then select the ROM you wish to play. Once in the game press TAB to get into the menu. From there you can edit the input map for the emulator menu and the input map for the game itself. To re-map, simply select the function you want to reassign, press enter, then press the button or joystick direction you want to re-assign it with.