Open a browser, (IE or firefox),in the URL address bar type in 192.168.1.1 or 192.168.1.100 and see do you get a connection to your routers configuration page. If you dont then you'll have to talk to the person who configured the router for you.
When onthe config page you should see a few options one of which should be wireless config or wirelesss security, somewhere under there you should have WEP configured, and the keys will be displayed.