41849 HTML, 10-minute project

So there is this article on alternative style sheets [login to view URL] and everything seems easy and understandable, but somehow I can't get it to work for me. I'm sure the only reason is a lack of experience. I will send you 2html files and 3 css sheets (2 for screen, one for print). All I need from you is to show me how to make a css change from preferred to alternative (in tutorial it's done over link, i would like this link to look as radio button)