A) Wordpress Plugin;
Download the Beacon plugin from https://app.thisisbeacon.com/plugins/Wordpress.zip, upload it to your WP site and activate it.
B) Template; Locate your footer PHP template and paste the following code before the </footer> tag in that template.
<script type="text/javascript">
(function(a, d, w){
var h= d.getElementsByTagName(a[0])[0]; var s= d.createElement(a[1]);
s.type= a[2]; s.src= a[3]; h.appendChild(s);
})(['head', 'script', 'text/javascript', '//tracker.thisisbeacon.com/tracker/'], document, window);
</script>