If what your friend wants is on boot to enter her account without having to provide the password, go to System Preferences, Security & Privacy, General tab. Unlock the pane by clicking on the lock icon and providing an administrator's password, then uncheck "Disable automatic login." Now when the machine boots, it will automatically enter whichever account is set up first in Users & Groups (I think that's the default). But she will still have to provide an administrative password to install software, etc.