.html not needed at the end of the url?

["LHUNTERJR" <webforumsuser@xxxxxxxxxxxxxx>]

Hi, I an new to web design and this might we a really stupid question but I am 
trying to figure out how I create a site that does not require the .html tag at 
the end of the url.
 Example
 http://www.fox.com/backtoyou/  or
 http://www.gospelmusicchannel.com/artists

 I have created my site and all of the pages after the home page require .html 
to be at the end in order to view that page.  How to make the above examples 
happen?