The MP3 player is a media player, sampler, and looper in one module All you have to do is upload your MP3 files to the provided SD card and snap it to a speaker Bit.The mp3 player reads mp3 files off of the SD card that is underneath the bit. To choose the order that files are played in simply rename the mp3 file so that it has a number in front of the file name. The mp3 player will then play your mp3 tracks in numerical order.Use the 'back' and 'forward' buttons to switch between tracks on the mp3 player. If you are in the middle of a song then double click the 'back' button to go to the previous track. Playback is started by sending a pulse or latch through the input signal line to the bit. The behavior of playback thereafter depends on which of the four modes is selected.