Go to
http://www.bjcp.org/2008styles/catdex.php and look at the different styles of German Beer (For example, under category 1 - Light Lager, you will find a subcategory 1D for Munich Helles). At the bottom of each subcategory description is a listing a commercial examples that fit the subcategory. That is a great way to learn about not only how the styles (category) and subcategories, but also about the range of the categories and subcategories. Another great resource is
www.germanbeerinstitute.com . The owner of that site is a German and provides a pretty good description of German styles and their history. Finally, we can't forget about
www.braukaiser.com which is Kai's (Kaiser) website. Kai is very active on HBT, is German, and a chemist... His site is fairly technical but helps with brewing good German beer! Good luck!