Showing Macbook screen on a larger monitor When I connect the Macbook to a TV monitor it does not duplicate my screen.  It shows the Yosemite screen.  It doesn't change as I open different files.
Go to System Preferences > Displays and turn on Mirroring. This will duplicate the main window onto the TV monitor.

You can alternatively decide to put the Menu Bar at the top of the TV monitor instead of the MacBook, or choose to put the menu bar at the top of both screens. These preferences are found in the Displays Preference Pane.

By default, the split screen puts the secondary display (the TV monitor) to the right or left of the main (MacBook) screen. Move the mouse pointer off the right or left edge of the MacBook screen and see if the pointer appears.