Apple podcasts, the most popular podcasting platform, accepts new podcasts through podcastsconnect.apple.com. You'll need a ready-to-go RSS feed with all the right meta data and images for your show properly coded in there. If you use a host like Buzzsprout, for example, it'll be an easy one or two clicks to get your show on Apple Podcasts and other directories to help you get your show up and running, fast.