That depends entirely on which graphics card you have, and whether it has TV-out.
Some have a yellow phono socket for composite out, in which case as long as your telly has phono inputs you just need a phono-phono lead for the video and a 3.5mm jack to 2 phono for the audio. Alternatively you can plug these into a scart adapter as you wish.
Some have a 5-pin mini-din S-Video output, in which case as above but using an S-Video lead.
...and some have a different or bespoke connector often with a lot more pins, to which you connect an adapter which came with the video card or PC, this then has a few different sockets on it to connect by various means, usually the ones I mentioned above.
If your graphics card
only has a 15-pin D-sub connector for a monitor then it's not quite so simple, unless the TV can take a D-sub connection itself, you need a device to adapt it which could be prohibitively expensive, and instead I'd consider upgrading to a video card that does have TV-out because you also get the benefit of an upgrade at the same time.
Hope this helps, any questions then fire away
