To log in to a session, perform the following steps:
When you log in successfully, GNOME will take a short amount of time to start up. When it is ready, you will see the Desktop and you can begin using your computer.
The first time you log in, the session manager starts a new session. If you have logged in before and saved the settings for the previous session when you logged out, then the session manager restores your previous session.
If you want to shut down or restart the system before you log in, click on the System icon on the login screen. A dialog is displayed. Select the option that you require, then click OK.
Your system distributor or vendor may have altered the login screen so that it no longer has a System icon. In this case, the option to shut down the computer may be found by clicking the Other icon, or by clicking a separate Shut Down button.