I recommend moving your css from the inline scope. Assuming that your .png file actually exists, try setting the background size and repeat tags.
<!DOCTYPE html>
<html>
<head>
<style type="text/css">
body {background-color:gray;}
#mydiv {
background-image: url('/ximages/websiteheader1.png');
background-repeat:no-repeat;
background-size:contain;
height:200px;width:1200px;
}
</style>
</head>
<body>
<div id="mydiv">
</div>
</body>
</html>
If that doesn’t work, try checking in your browser’s developer tools for the response codes and making sure that the url is correct.
Hope this helps!
