whatever goes here...bla bla...etc.
you find the detailed description at this link: introduction.
in short, the necessary CSS is added via CDN in this example. to avoid that you could download bootstrap.min.css, add it into the same directory your HTML file resides in, and link to it with link rel="stylesheet" in the HTML head. you could even include it literally between style-tags in the HTML head. this would make the HTML file a lot less clear though.
if you want to use this yourself you'll have to read thru some of the instructions listed in the introduction page, particularly:
the rest is interesting too, depending on what you want to do, what you want to include in your web page.
as it is, all you need are the images and this HTML file in the same directory and your page will display fine.