Gameboy Advance -
Nintendo 64 -
an emulator is software that emulates a particular game machine(console or arcade) and the rom is the file of the game, so you need to know what type of game rom you have and get the proper emulator.
For example: A Rom will be a certain game for the Gameboy Advance, Pokemon Emerald.
If you need a tutorial, I recommend searching one on youtube, These links are totally legit, All credits go to the makers of these emulators and roms.
ROMS:
