After a couple days work, I can now import and export OPML files with my RSS reader. These files are used to transfer lists of your feeds between RSS readers. They have category names, and then the list of RSS feeds in each category. Each feed has the title and the URL to the RSS feed. So now I can import and export, and I can edit my feeds. I did some cleanup of my existing feeds. I have 162 feeds. That was a shock. I thought I was following about 30 feeds. I have more than 30 history podcast feeds.
So I wrote code to clean and edit my feeds and sort them and organise them, and link to the original website and to the feed. I've learned a lot in the process. I learned a lot about RSS when I had to quickly provide an RSS feed on my blogs after I left WordPress, but now I'm learning a whole lot more.