After extensive research, I have tried
background-image: url("/images/image.jpg"); ../../images/image.jpg ../images/image.jpg /images/image.jpg ./image.jpg And the entire URL. Plus others. I don't know what I'm doing wrong.
The path is forward one directory.
This is my CSS:
nav { background-image: url ("./images/navmenu.jpg"); width:100%; height:200px; margin:0; display:block; padding:0; } 
"/images/image.jpg"doesn't work, that means that the picture is not at"/images/image.jpg".