After 100s of mistakes & re-reading over and over again General Winter's instructions, I finally figured out what I was doing wrong! I was not interpreting the instructions correctly so everything I tried to do was wrong. I have been so excited that I have spent 10 hours today doing nothing but making photos with layers. I am still making mistakes, but not about how to make the layers--just from experimenting around with some of the other features. But I tell you one thing that I learned, something that may help others--when you are making a second layer with a portrait, try not to use one where someone is wearing a navy blue shirt and the original background with that photo was black! When I was erasing the black background from around my grandson's pic, it was almost impossible to see where to erase next to his navy blue shirt--it was almost the color of the black background. Did a lot of undoing with that problem! Next time I will make sure either the clothes are dark with a light background or the clothes are light with a dark background before I paste a second layer! I also found a site that has lots of instructions for using GIMP if anyone is interested in it. Here is the link:
http://docs.gimp.org/2.6/en/index.html

I guess we can call this thread solved, at least until I get stumped about another problem I can't figure out with GIMP--will just post a different thread if I do.
Thanks everyone,
Sheila