How to remove vocals from shows?

I downloaded a video (Courage the Cowardly Dog) and converted it to a
mp3. I'm trying to remove the vocals to listen to the instruments in
the background. I'd very much like some help. I've tried using the
audacity method, but it hasn't worked for me. I'm using a Windows XP.

As a side note, I'm unfortunately not tech savvy in any way. A step by
step instruction would be very much obliged.