Thanks for the comeback, Jeremy. I hope you will stay with me and help me work through this.
Let's try the first solution mentioned - manually adding items to my device (iPod). OK - I have the latest version of iTunes (V. 12.6.1.25). I have my iPod connected to a USB port and iTunes is recognizing it. "Mike's iPod" is listed in the left-hand column and there is a very small, iPod icon in the upper left area of the iTunes window. I make sure my iTunes library is in the main window - not my iPod music. I then select the song I want to copy. I left click on it and drag it over to "Mike's iPod." As I hover the cursor, it blinks, indicating (to me anyway) that the song will be copied onto the iPod when I release the mouse (same as copying a song into a playlist). I release the mouse. I go to my iPod. The song has not been copied. It isn't there.
Am I leaving anything out or doing anything wrong?
There is another way to manually do it that is not mentioned in the article. I select the song I want and then right click on it. A menu pops up inviting me to "Add to Device." The extension of that menu item says "Mike's iPod." You would think, wouldn't you? But no, of course not. Doesn't do diddily. I click on it and nothing gets added to the iPod.
Second suggested solution to follow ....