To create MP3s you will need to connect a cable from the output of your WK1800 to the input of your computer soundcard to record a WAV file and then run any software that can convert the WAV file to the MP3. You will probably just need to buy an inexpensive adapter to allow you to plug your stereo 1/4 phono jack to a 1/8 mini jack that will plug into your soundcard. Radio Shack or a similar electronics store will be able to provide this. Then you will have to experiment with sound levels so you get a good signal that doesn't distort or get too weak.