Thanks to all of you for helping me to understand how it works. Unfortunately, when I tried to open the file with (what I thought was Writer but was any of them as I now understand) it was saved with the SLSX extenstion, LibreOffice gave me a message that the file was corrupt. I selected the try to fix option, but they couldn't repair it. I had another option to save the file in the .odt extension, but that didn't work either, so it must be the file itself that is the problem. I'll contact the creator of the file.