Did you look at the page's source? There's the answer. Still, did you also look in a CSS reference guide?
http://w3schools.com - There's enough reference for you.
Make sure you look at the page's source when you want to find out how it's done. If you are looking for the CSS, it may be written inside that same page, or a .css document could be linked to it, in which case, just copy the address and paste in in your browser, and try navigating to it.
If you need more detailed instructions, let me know.