How do I block a website on a Macintosh computer?

I need to block access to a specific website on a Macintosh computer. I have blocked the website from all of our PC's in the office by editing the "hosts" file, which worked great. However, I cannot figure out how to do it on a macintosh. Any suggestions? Some will probably suggest "Internet Tools" and then "Security" and add the website to the restricted list, but that doesn't block it... I need a way to completely block it. Thanks!