Mozilla is a browser based on open source code. It is not the same as Netscape, but there are large similarities since Netscape (which is a commercial product) is also to a large extent based on the same code.
To be able to access the internet outside the university you have to configure it to use a proxy and authenticiate yourself with your e-mail account. Select "Preferences" from the "Edit" menu in mozilla. Click on the small arrow next to "Advanced" and select "Proxies". Select the "Automatic proxy configuration" and type in http://proxy.umu.se as the URL.