Ok…so you should take this video:
or another one if you find a better one.
Copy and paste the URL into this website: http://www.video2mp3.net/
Then go through the steps to download. I know there is a pop-up but its fine…just close it and keep going. Once you download it should appear in your downloads folder.
If iTunes is your default player, then you can just click on the mp3 and then it should automatically put it into your iTunes for you.