Hello,
Our help page explains what would go there and gives an example related to Google AdWords.
If you don't have an AdWords Tracking Beacon then you don't need to use this code, you can just stick with the Google Analytics code provided at the same help page. That code will already automatically track conversions as part of Google Analytics:
<script type="text/javascript">
var gaJsHost=(("https:"==document.location.protocol)?"https://ssl.":"http://www.");
document.write(unescape("%3Cscript src='"+gaJsHost+
"google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E"));
</script>
<script type="text/javascript">
var ejGATracker = gat.getTracker("UA-XXXXX-X");
ejGATracker._setDomainName("none");
ejGATracker._setAllowLinker(true);
ejGATracker._trackPageview();
</script>
(be sure to replace UA-XXXXX-X with your own ID)