All code update servers seem to be unavailable - automatic proxy?

When trying to "load code updates" I get the error message "All code update servers seem to be unavailable". The network uses an "automatic proxy configuration URL" like "http://###.###.###.###/proxy.pac"

I have just installed Squeak and finally managed to get it to look a bit better. Now I want to install Seaside using SqueakMap package loader but I can't seem to get Squeak to find the Internet.

How do I set proxy settings in Squeak? I tried to save changes in "http proxy" using the "Preferences browser" but it doesn't seem to save my changes? How do I add seaside to my image?