If your site is based on a Dreamweaver template you can add
the code to txhe template and update the website, or get your
webmaster/developer to do that.
With Contribute CS3 you can add HTML-snippets, if allowed by
Earlier versions allow you to edit the source code (if you
have the proper rights), so it's possible to insert the code of a
counter (statcounter.com) into the page (File, Actions, Edit source
in external app).