If you are having issues with your web pages not displaying background images and you are using a masterpage, the problem could be because the path to the image is relative to the page itself and not the masterpage.
To fix this issue, add a link to a CSS file in your masterpage instead of using inline styles.
<link href="css/Main.css" rel="stylesheet" type="text/css" />
This makes the image path become relative to the linked CSS file instead of the page.
