How to configure proxy in linux?

[Nuno]

Hi all. I´m starting with linux for the first time and I have to configure my internet connection. My ISP requires that the connection be made to their proxy server. Now, in windows 9x it´s easy, I counfigure it in the browser in the internet options. In linux I can´t find it anywhere.
The proxy server should be proxy.esoterica.pt in port 80.

I´m using Redhat 5.2, kernel 2.0.36, Xfree 3.3.2, Netscape Navigator 4.07.

Thanks very much to anyone who can help me