Migrate Feed Podcast Jekyll to Hugo

Thanks frjo.
I try to understand hugo structure. My English is horrible.
I don´t know how add length mp3 code. Sorry
I create a repository in gitlab: https://gitlab.com/podcastlinux/hugopodcast/
I create a index.xml in layouts folder. I think it´s ok: https://gitlab.com/podcastlinux/hugopodcast/blob/master/layouts/index.xml
Now i want generate feed only post with a specific category or tag.
Something like

But it´s very difficult for me.

Thanks for help everybody.