In your example - whereby a visitor came to your page via Google - Google is called the referer (no, that's not a typo!).
While it is technically possible to see where your visitors came from (again, the referer), using a server log analysis tool, your hosting company's server must cooperate to a certain extent - and this is not always the case (especially if you're not using a paid hosting service).
A popular server log analysis tool is:The Webalizer
You may want to check out their FAQ section first.
However - you've indicated that you do not host the website. Typically server log info is only available to the Webmaster - and many hosting companies have their own proprietary server log analysis tools that they make available to the Webmaster - but I'm not sure if this would apply in your case...?
Edited by The Architect, 05 May 2006 - 08:19 PM.