Let see if I can simplify this....
Co-dom= A gene that will show up or not. The genes dont hide, like recessive genes (albino, pied, etc)
Ex: A Pastel(Co-Dom) + Normal = Both normal and pastel babies
An Albino(recessive) + Normal = All 100% het for albino (all normal looking snakes that carry the albino gene)
Hope that helps..
Heres a great site for learing bout balls
http://www.ballpython.ca/gallery/breeding.html