The instructions for what to do are actually on the page you directed us to. It's just that you don't know enough about the different markup languages to even know that they are instructions.
So here we go: Put the CSS code provided on that page at the bottom of your theme's styles.css file. Then, when you create your posts, use the html editor, not the visual editor and put in the HTML code provided on that site.
If that doesn't make sense to you, or you want it to work differently than it does, refer to my earlier post for options about learning the different coding languages.