Graphics file

Hello, I need some help with Editor workspace and selecting Graphics.

I want to add my images to the graphic catalog in PSE 2020. I used to be able to do that in a previous version, but the method I used does not work with the 2020 version. My images are included when I am in Editor and I select Graphics to add a background, but I get an error message that says the image can't be found. So, I have two questions: How can I add my own images to the Graphics file and 

                  Why am I getting an error message when I select one of my files?