Your files are probably located in Pictures.
To go to Pictures, do the following.
1) Open the Finder window.
Do one of the following.
• In the Dock, click the Finder icon.
It has two faces.
• Press Cmd + n to open a Finder window.
2) Look for Pictures in the bottom half of the sidebar on the left side of the Finder window.
3) Double click Pictures, and browse to the desired file.
Your files may be in folder that:
• Has the name of your camera manufacturer
• Is the year the photograph was taken.
• Or ?
Do the following to open a file.
1) Open Photoshop Elements.
2) Go to File > Open, or press Cmd + o.
A Finder window will open.
3) Double click Pictures.
4) Browse to the file.
5) Select the file.
6) Click Open in the bottom-right corner of the Finder window.
When you double click a file, your computer is set to use a certain program to open the file.
This default setting probably isn't Photoshop Elements.
If you'd like to open photographs in Photoshop Elements when you click them in Pictures, go to Open With.