Hmm, bit of a strange topic for a forum about recording, but anyway, welcome!
Depends on the outputs you have available from your graphics card and the inputs available on your TV...
Some newer TVs have straight-up D-SUB VGA or DVI inputs which mean you can connect your TV to your computer as you would a monitor. Some graphics cards have HDMI which is also good for connecting to new'ish TVs.
For older TVs you'll be looking at something like S-video or composite to connect to your TV - don't expect anything great from this; bad quality 640x480 at the most. Quite a few graphics cards from a few years have S-video on them (before HDMI caught on). Have a check to see what your computer has.