First all, apologies to Rick Brewster. I really appreciate having free access to such a well regarded programme. On reflection, it incorrect to imply that the developers should also donate an accompanying free book to the world. However, perhaps some other skilled contributor(s) to these tutorials would be prepared to take up the torch and run with it, by donating a Basic Manual to this website.
Something similar to the three projects by Ms.Rouse (Google, ‘Paint.NET Kathy Rouse’) plus thumbnail/graphics additions and links to specifics in the tutorials, would make an excellent starter manual.
In the meantime, I have taken an initial look at recommended advice locations and see much very useful information. Many thanks Contributors for making the effort to help me; there is lots of relevant detail, which will take me quite a long time to study.