You will need your server to serve styleguide.html someplace in your site.
Setting up a route for /styleguide/ is ideal. You may want to consider if you
want your styleguide to be publicly accessible or not, and apply permissions as
appropriate.
To set up the styleguide, edit styleguide.html to include links to your own
site's CSS assets. The javascript dependencies that the styleguide depends on
(other than its own styleguide.js) are included via CDN - you can swap these
links out if you would prefer to host locally.
You may want to add some additional markup so that the styleguide can be embedded more gracefully in your site, e.g. by adding your normal site navigation before the styleguide HTML starts.
Finally, start adding your own section block in styleguide.html to document
the HTML markup for commonly used components in your site. As the file uses your
own stylesheets, the markup should automatically inherit the correct styling,
and update itself as your styles evolve.