Hi Mary,
I'm not clear on what happened, but I'll try to help. Photos app should be found in your Applications folder. You can find the Applications folder from the Finder by looking in the Go menu - it is near the bottom of the list. It may also be in the left sidebar of a Finder window.
There is a Pictures folder in your Home folder where the Photos app's library is normally found. Home folder is also listed in the Go menu.
I'm not aware of any Photos folder created by default. Perhaps we can look at your screen tonight.
Jim