Note: You need administrator privileges and your UCSD network username and password to authenticate your computer with the proxy server. If you've forgotten your username or password, see Getting or Changing UCSD Passwords.
As an alternative, you may want to consider using the Virtual Private Network (VPN) to access UCSD-only resources. Users tend to find this setup easier to use. The Cisco VPN AnyConnect client via convential installation seems to be the preferred method.