how to display background in dynamic html pages with DOM

Question

Hi, below code is  related  to displaying banner and background in dynamic html pages. Banner is displaying in html pages but background is not displayed
<?php
require('simple_html_dom.php');
$banner = $_GET["banner"];
$background = $_GET["background"];
$z="uploadbanner/";
a="uploadbackground/";
$bannerid= substr_replace($z,$banner,14,0);
//$backgroundid= substr_replace($a,$background,18,0);
$html=file_get_html("player.html");
$ele3=$html->getElementById('test3');
//$ele4=$html->getElementById('test4');
//$ele4->setAttribute('src',$backgroundid);
$n=file_put_contents("$name.html",$html);
$page=$name.'.html';
?>
player.html:
------------------
<img id="test3" src="" width="1600" height="200"> //for displaying banner
------------how to write code for background----------------