In order to get jQuery-functions available to your webpage, you need to add the jQuery library as part of your page. This can be done by adding a script tag, which will reference to jQuery online or to a local file.
<script src="https://code.jquery.com/jquery-3.1.1.js" integrity="sha256-16cdPddA6VdVInumRGo6IbivbERE8p7CQR3HzTBuELA="crossorigin="anonymous"></script>
Go Ahead and add the line above to this pages HTML-code. Then reload the page. You can make sure that jQuery is up and running by typing $ at the console.