1) What is a spout?

-- a spout is a special type of feed (github, twitter timeline or acoount) ... there are a bunch
-- they show up in a <select> element on the Sources page, when adding or editing a Feed you'll interact with this form field

2) OPML is fickle, or you might not have an OPML file to start with ... So how do you add a feed?

-- navigate to yoursite.com/#sources or yoursite.com{base_url}/#sources

... from there you can add / edit feeds & import / export OPML files, too.

I'm not sure if a button is supposed to exist in the UI for this -- but it should so ...

3) All the the site templates are in /templates & are pretty straight forward

-- I added a link to home.html near navigation that linked to href="#sources"

And to add a new feed without OPML import, you do what?

There is a concept called Spout, which is what?

If you wanted to to use the REST API to add a feed you'd do what?

I think answers to those few questions would help a lot ...

Although maybe there's something broken in my install & I'm just missing the link to add feeds or the "welcome to selfoss, here's what you installed and how it works" ...