Located the OGG folder in LFS/DATA/OGG. Here the music in-game are to be found. To add music you need to convert files into ogg. format. For example google "Mp3 to OGG convert" , and you'll find various programs for it. Normally you can with these progams open a wished MP3 file, save it as OGG and place it in your OGG folder in LFS.
Inside LFS you need to make new radio channel to play the new music. Go to audio, here you make a new radio channel, then you make new track/name/song ... don't remember name on this one but you'll see there. Then you edit the radio channel, and mark every song with "1" . This can be done on right side of the song, by some options there.
Sorry the fussy explenation, but you'll see it when you are there, just ask here if there is problems, and we'll try to help