From user manual (page 68):Your computer comes with a built-in display panel, but you can also
connect an external display device to an available video port, as
❖ An external monitor or projector via the RGB (monitor) port
❖ A TV, VCR, or DVD recorder via the S-video (TV-out) port
Before connecting an external monitor or video projector, configure
your computer for the type of device you are connecting. To do this,
refer to the documentation for your operating system and devices
So you have to use an RGB cable or a S-video cable : your cable should be plugged into 15 pin VGA port in your PC and plug it into a correspondent port in your TV.
Try also S- video and select correponding input in your TV set (Both connection type DO NOT carry sound: use your audio connector from PC to TV audio input.)
Configure your extended screen using your manual instruction:Once you have connected an external display device, you can
choose to use the internal display only, the external device only, or
both simultaneously. The quickest way to change the display output
settings is to use the display hot key (Fn + F5):
1 Press Fn and F5 simultaneously.
2 While holding down Fn, press F5 repeatedly until the setting
you want takes effect. Briefly pause each time you press the F5
key to allow time for the display to change.
This hot key cycles through the settings in the following order:
❖ Built-in display only
❖ Built-in display and external monitor simultaneously
❖ External monitor only
❖ Built-in display and TV
❖ TV only