The fact that you are reading this page shows that Privoxy was not used in the process of accessing it. Had the request been made through Privoxy, it would have been intercepted and you would be looking at Privoxy's web-based user interface now.
So what went wrong? Chances are (in this order) that:
this page is in your browser's cache. You've once been here before starting to use Privoxy, and now your browser thinks that it already knows the content of this page. Hence it doesn't request a fresh copy.
Force your browser to do that. With most browsers, clicking "reload" while holding down the shift key (shift-reloading) should suffice, but you might need to manually clear the browser's cache (both memory and disk cache).
your browser is not set up to use Privoxy.
Check your browser's proxy settings and make sure that it uses 127.0.0.1, port 8118 (or, if you did a custom configuration, whatever different values you used).
when using multiple proxies in a chain, that either the chain is broken at some point before Privoxy, or that an earlier proxy serves this page from its cache.
If you have read the user manual and still have trouble, feel free to contact us to get help.