What are you using for a testing server on your local machine?
MAMP is the most common for macintosh
by default, MAMP will create a folder in the applications folder that maps to the http://localhost address:
/Applications/Mamp/htdocs
you would pput the site files inside that folder
/Applications/Mamp/htdocs/your_site
and set the url to:
http://localhost/your_site
by putting the files in your users folder, it is not in a location that the local host address would map to.
see the tutorial for details on defining a site:
http://www.webassist.com/tutorials/Define-a-dynamic-site-in-CS5
and this one for details on installing a local testing server:
http://www.webassist.com/tutorials/Set-up-a-test-server-on-Mac-OS
