The only way to find a podcast is via search. There is a "Podcast Map" which ought to be a topic oriented browsing system, but instead you have an alphabetical index of the known podcasts they track. Yup, the "Map" has a list of the letters A-Z and on each one is listed the podcasts whose name starts with that letter. How are you supposed to find anything with such an index?
It's free to add a podcast URL.