Does anyone know how to cross two phenotypes together?

How do you cross two genotypes together? for example, I'm doing a mice prject webquest for my biology cl and to get a mouse with black fur and black eyes, the phenotypes are BBEE, and to get a mouse with white fur and whites the phenotypes are bbee. i know you use a punnet square to cross them together but im not sure how that works. can someone help? : ) thanks