if you have an HDMI out on your laptop and an HDMI in on your computer, plug it in. Then switch the input to that HDMI line. You will have to turn sound on in sound settings to send it via the HDMI out on your computer (and have it set to receive sound on the HDMI in on the tv).
If you do not have this you may have a computer VGA out or what ever the wider one is called and you can use that but sound wont travel.
I use HDMI on mine, if all you have is component or RCA things hmm not sure without an adaptor of some ort.