Read the LWP::UserAgent documentation which contains a really good bit about using proxy servers. It is explained in detail.
What are you trying to achieve? If I follow the tortured thread of your previous postings then I don't believe that the proxy server will do what you want it to do since the communication will still originate from your machine.
You can try it with your browser. Start up your proxy, fill in the IP and port into your browser preferences for proxy, and provided the proxy can access internet, you should be able to reach the WWW in your browser.
BTW you can set up Apache as a proxy server, in addition to a local web server, too. In general, that'll be a more satisfactory solution.