The first step in installing a doggy door is finding a location, and a doggy door will come with a paper template that can be taped to a door to guide the process of drilling out a hole. Learn about the magnetic catch that exists on the bottom of many doggy doors with help from a home remodeling specialist in this free video on installing doggy doors. Expert: William Perkinson Bio: William Perkinson is a partner with Perkinson Building Corporation, based in Birmingham, Ala. Filmmaker: Tim Brown