For simple web installs you need to add our official script to the page and run it. Here is an example: 
<script src="https://cdn.visitorquery.com/visitorquery.js"></script>
<script type="text/javascript">
	window.addEventListener('load', () => {
		window.VisitorQuery.run({
			ApiKey   : "<project-public-api-key>",
			SessionId: "session-id-of-the-user"
		});
	});
</script>
That’s pretty much it, place this code on any page or on the pages where you want to perform the checks. Ideally, before you need to check the results.