Hey Fred, I did a short 6 min video for what you are wanting to do. Just so you know, @Steve has far more knowledge then I do, concerning Audacity. The way I did it was using the "Split" command under the Edit Menu / Clip Boundaries / Split. You can view it here. https://youtu.be/r1yQQDOnC90
@Steve, I downloaded your recommendation and will play with it later this afternoon. Thanks for the info.