It's very simple. First insert your memory card inyour phone so it can create the files. Then connect to you computer using the usb that comes with your phone. Right click start and go to explore. Go to you file that has you music. Highlight the song you want and click on edit, copy to folder, and find your memory card there should be a file for you audio. You copy it to there. Depending on the size of your memory card you can download alot of mp3s.
