I actually learned a lot of it taking genetics in college. All of the corn morphs (so far) are recessive, so once you understand simple Mendelian genetics, its a breeze. You just have to know what makes what (i.e. anery A + amel = snow).

Here are some good sites to help you out.

Genetics basics: http://www.serpwidgets.com/Genetics/genetics.html
Morph Info: http://www.serpwidgets.com/Morphs/morphs.html
And a great book to own: http://cornguide.com/the%20guide.php