http://americanboxerclub.org/health-screening.html
This link will show you the health screenings that should be done before you even think of breeding your boxer. That is assuming you even wish to consider going about it the right way instead of joining the ranks of backyard and puppymill breeders.
If you got your boxer from a responsible breeder, there's a good chance she was sold to you on a limited registration. If this is the case, and you breed her, the litter would not be eligible for registration. If you got her from a pet store or some backyard breeder who did what you're indicating you want to do (bred for color or other single trait), then your dog is not breeding material. Spay her and enjoy her as a loving pet. You will save yourself and possibly her from a lot of potential grief.