The TV will have either an analog video port, an HDMI port or a vga port
If its a Mac it will likely have either a display port or mini display port... you will have to buy a converter.
If its a PC brand, it will more than likely have a blue multi pin port for VGA. You will need to buy a vga to composite video plug (its a round yellow plug with a single connector in the middle. If you have an HDMI or DVI (DVI is normally white) you cannot connect if you dont have those ports on your laptop without spending a lot of money to convert the signal. The deal is VGA is analog and DVI/HDMI are digital.
There are a whole lot of variables in what I just said so more detail will get you a better answer....
and BTW, unless you use HDMI or DP...