Converting to MP3 Files? DP-004 Recorder?

Ok, I payed a ton for a DP-004 Recorder, and I'm having a ton of trouble. I saved the song I made into a backup file, and connected the USB. The screen came up and I opened the BACKUP folder. It had my song in it, but It wasn't an MP3, it didn't run on any program. I tryed opening it with a bunch of programs, but none seem to work. Please, I can't find anything online. Help me