[LAU] Equilization dah?

I have read that using equalization will give each instrument more "space" and make the track clearer and easier to listen to. I sort of understand that this involves removing some frequencies from, say the guitar, so that it does not interfere with vocals, or some such concept. Is there somewhere on the internet I could get some information or better yet, some real life examples, of how to equalize a track? I use Audacity as a sound editor and it does have EQ on it, but I've no idea how to use it. Is there somewhere on the internet that can tell me what frequency ranges the typical bland human voice, harmonica, guitar, bass, and drums each cover individually? That way I'll have a starting point for this adventure into EQ. Or is learning EQ just a case of sloppin' around until something good happens?