Setting proxy for apt-get

Hello

I installed the Ubuntu server on my old Mac G4, and it's working great.

Unfortunately, we are inside a closed network here at work, and we use a proxy server to access the outside world.

I'm new at the Linux thing, and I don;t know what to do to get apt-get (or any other app, for that matter) to properly access the proxy server to get out on the internet.

Please advise. Thanks for the help.

---------------------S