Take an SD card that has been formatted with FAT16 or FAT32.
Create a directory named SNES at the root of your SD card. Inside the SNES
directory, create another directory named ROMS.
This directory (/SNES/ROMS/) is where you should put all ROMs and music files.
The currently supported file types are:
*.SMC (SNES games)
*.SPC (SNES music)
*.VGM (uncompressed Sega Master System / Game Gear music)