A podcast episode consists of a WordPress Post and one or more media files. The content of the post is used as the summary for the episode. If you only have one type of media for all your episodes then you just need to add one media file to the post.
If you are going to submit your podcast feed to iTunes then you must consider the content of your post. iTunes does now allow html code to be used in the summary field of the podcast feed so you’ll need to address this issue.
We strip the HTML from the post (as of 2.3.8) so this might make things look a bit out of place. As an option you can add a custom field with the tag ‘itunes_summary’ to your post. Anything you add to this tag will be used instead of the post content for the summary field.