So you have a lead that goes from VGA connection on one side (for laptop), to RCA connectors for component output on the other side, which your TV has?
Connect them, and on your TV set it to AV-3 or whatever it's called (how to do this and what it's called it dependant on your TV. It's probably the same thing you do to change to VCR or cable).
You may have to press something like Fn+F5 on your laptop, or something like that (look at the picture on the key), to get the laptop to swap between showing pictures on just laptop screen to on both screens at once.
This depends on your laptop and which operating system you're using though.