Are web sites available to teach topo navigation?

I was wondering if anyone had any suggestions as to web sites, FAQs,
or other Internet available documentation on how to read TOPO maps and
the basics of navigation.  I recently purchased a Garmin Map 76S GPS
unit, and subsequently realized that I need to learn a lot more about
navigation in order to put it to good use.  Thanks so much in advance,
Richard Dillon