Here is a proxy add on for Firefox
https://addons.mozilla.org/en-US/firefox/addon/2464
To enable proxy settings in Firefox 3.0
Select Tools -> Options. ( In some Firefox browser's you have to go to Edit>Preferences usually in LInux )
Select
Advanced.
Open the
Network tab.
In
'Connections' area click '
Settings' button.
Select
Manual Proxy Configuration radio button.
In the necessary proxy field(s), put the same settings in the HTTP field then
Click 'OK'