If they are stored in MP3 in Itunes ;-
Real simple way on a PC is to right click on the track in iTunes and select Copy, then browse to your SD card in explorer, right click and Paste
Harder way but better especially if you want a whole album is to locate where the tracks are stored, right click in Itunes, Get Info will show you where the file is stored, then in Explorer locate the folder and copy & paste to the SD card