All you need are three lines in your HTML file.
<!-- GOES INTO HEAD -->
<link rel="stylesheet" href="http://lengthylyova.pythonanywhere.com/static/gh-contrib-graph/gh.css">
<!-- GOES INTO BODY -->
<div id="gh" data-login="YOUR_GITHUB_LOGIN"></div>
<!-- GOES INTO THE END OF BODY -->
<script src="http://lengthylyova.pythonanywhere.com/static/gh-contrib-graph/gh.js"></script>
-
Replace
YOUR_GITHUB_LOGIN
with the GitHub Login of the user whose data you want to graph.