mootool display image

Question

i want to display image after it upload using mootools

i write following code but it did't work

    onFileSuccess: function(file, response) {
            var json = new Hash(JSON.decode(response, true) || {});

            if (json.get('status') == '1') {
                    file.element.addClass('file-success');
            } else {
                    file.element.addClass('file-failed');
            }
    })

and li is

     <li class="file file-success">
     </li>

the file-success class is

 #img-list li.file.file-success {
    background-image: url(uploading/assets/uploaded.png);
 }

and my php return image name after uploading like this

   $info1='../uploads/' . $newfilename; 
   $return['fpath'] = $info1;

in place of uploaded.png i want to show image with is return by php in

  $return['fpath'] = $info1; statement