How i can setup a proxy in Windows? N00b Question!

Please anyone can help me? How i can setup a proxy (with username and password) in Windows XP 32bit?

I have tryied Foxy Proxy but it don't ask me for the login...so doesn't work...

Any help? Thank you so much!

didn't you try a public proxy by chance? try a private one, foxy proxy is a good addon, it has to work
or if you're using firefox, you can also try to configure your network settings here: Tools/Options/Advanced/Network/Settings/Manual Proxy Configuration

yes i use foxy proxy but i need in all the system

However i have contect the support of my proxies and they have told me that the port 80 it's closed...so i can't use it on my software