There are several good explanations right here on PhotoCamel, check out these tutorial threads.....
http://photocamel.com/forum/hdr-high...-tutorial.html
http://photocamel.com/forum/hdr-high...hdr-photo.html
http://photocamel.com/forum/hdr-high...5-minutes.html
These threads are found in the Photography by Genre: Critique and Discussion in the section called
HDR (High Dynamic Range) Photography. There are also lots of examples from other members of the group posted there.