A few tries, go to the apple in the top left and choose SYSTEM PREFERENCES....it should bring you to:
In the HARDWARE row you should see DISPLAYS. Select that and you will be at:
You have the DETECT DISPLAYS button, and also CLICK the "Show displays in menu bar" box, so you dont have to keep going through menus to configure.
If you look at the F7 key, to the right of the NUM LOCK key (F6), that key allows you to switch from expanded to mirroring or vice versa.
You can also check Apple's Knowledge base....
Keep me posted.