All you need to do is follow these 2 easy steps:
- Host your JavaScript content on an html page somewhere of your choice. In this example we'll be using a page I setup at http://bannerjsad.ning.com/navigator.html
- Add the JavaScript shown below in the Analytics box of your network. You'll need to change the "src" attribute for your iframe to point at the page you setup in step #1. You'll also probably want to adjust the height of your iframe so that it matches the content you're showing.
<script type="text/javascript">
x$("#xg_head").before("<div id='custom_banner'></div>");
var iframe = "<iframe src='http://bannerjsad.ning.com/navigator.html' scrolling='no' style='border:none; height:400px; width:100%;' frameborder='0'/>";
x$("#custom_banner").html(iframe);
</script>
Congratulations! You'll now see your JavaScript content in the header of your network.