Can someone tell me how to see who has viewed my Facebook profile?

Unfortunately, when my friends explained to me how to see who has looked me up on Facebook, I payed no attention. Now, I wish to use that service, but am having a difficult time finding it. If no one is able to help me, I can likely get the information tomorrow. I keep seeing that FB disallows this service. If anyone can direct me to a website, or application, I would appreciate it.