For adding an image as background for Advanced PDF template. Use below code
<?xml version="1.0"?><!DOCTYPE pdf PUBLIC "-//big.faceless.org//report" "report-1.1.dtd">
<pdf>
<head>
<macrolist>
<macro id="watermark">
<p><img src="Specify the image url"></img></p>
</macro>
</macrolist>
</head>
<body header="nlheader" header-height="10%" footer="nlfooter" footer-height="20pt" padding="0.5in 0.5in 0.5in 0.5in" size="Letter" background-macro="watermark">
<!---content----->
</body>
</pdf?