Dr. Drib, I spent another 20 minutes reading yesterday and made an effort to adjust my reading light and the angle(s) in how I held the reader. I'm happy to say that I had no eyestrain and no headache, so I'm encouraged. Thanks for sympathizing. I hope to learn more from reading this forum.
Also, many thanks to Dreams for the screenshots that will help me to learn my way around the forum. (Although I've 'registered' with many online forums in various fields, I've never used them much, but I'll try to follow this one more.)
Next I hope to install Calibre and manage and convert the ebooks I add.