HRL? I think that you mean URL ;-)
A URL (uniform resource locator) is simply a web address. It's probably best (but not essential) to have two tabs (or windows) open in your browser. In one tab go to the page where the YouTube video is. Right-click in the address bar and select 'copy'. Then, in the other tab, go to
http://www.listentoyoutube.com/ Right-click in the URL box, and select 'paste'. Click 'Go'. Then click 'Download MP3'. Repeat on the next page. When you're asked if you want to open or save the file, select 'Save to Disc'. Click 'OK'. Navigate to where you want to save the file, and choose a suitable file name. Click 'Save'.
Chris