You can use <script> to add the library in the HTML <head> or <body> tag: <script src='jquery-3.2.1.min.js'></script>
Write the code within the HTML document inside the <script> tag, here we have used cdn link.
<script src='
http://ajax.aspnetcdn.com/ajax/jQuery/jquery-3.2.1.js'></script>
<script type = “text/javascript”>
$(document)……… <jQuery code>
</script>
Include the .js file, which has the jQuery code into the HTML document.
<script src='script.js' type="text/javascript"></script>