@Peter_1985, I'm not sure why you are struggling to understand file paths on a computer system. Again, a 404 (not found) indicates the file path is incorrect or maybe the file does not exist on a remote server. The community cannot see where you saved the file on your system or the remote system if you've deployed the application.
I created an example where "pict" folder is in the application root and beautiful_Currency0e.jpg is inside the pict folder. The path function as expected and shows a background image. Please debug/troubleshoot.
<body style="background-image: url('/pict/beautiful_Currency0e.jpg')">