Lol at that... I've seen this on another site and you'd have to be retarded to get infected.
In a nutshell, you have to go to a website and download a dodgy looking 'Flash Player', and your browser will warn you to say it isn't signed, and the site looks really fake. Then all it does is infects your machine with a load of crap and uses Internet Explorer to send links using your Facebook account to your friends on FB, who would have to go and download, install etc...
Just don't install anything that looks a bit iffy and you'll be fine