Ah, now I know what my problem was. I had researched this before. I
also have an old tablet - Android 4.2 (jelly bean.) So, it is so old it may not work with the Chromecast dongle.
The article RamblingMad linked to kept saying, "Make sure your [device] is capable of Miracast." And I know my tablet isn't capable of it or other of the latest casting apps. So I had given up on the idea of a dongle since I have two dinosaur devices.
I DO have later generation devices. I know they wouldn't hook up
directly to the TV via their pre-installed casting apps or any I downloaded: Smart View, Miracast, Samsung Cast, etc. Tried all of them. Now, off to see which one I can hook up using a dongle.
Thanks guys!