You have to create persons in the database (with picture and profile address) before adding them to a podcast or to a specific episode. You may also specify a role if you want to.
Create a person simply by filling the fields:
Then add one or several persons to a podcast:
Add one or several persons to an episode:
Person added to a podcast are diplayed on the podcast home page:
Person added to an episode are diplayed on the episode page:
All person are exported to the RSS feed so that other podcast apps may use these information:
For instance, Podcast Addict will show all persons informations: