Either through a VGA cable or an HDMI cable. There should be ports on your computer that look like one of these:
The first is a VGA port, the second is HDMI. Look on both your laptop and the TV and find a port they share in common. (Either the laptop has a VGA port and the TV has one somewhere as well, or the same but with HDMI.) Then buy a cable of that type (don't overpay, hdmi cables can be rip-offs at places like office depot), plug it into both ends, and possibly hit the display button on the laptop. You're good to go.