If you want to connect it to your HDMI on your TV you will need to use the DVI port on your PC. You probably got an adapter with your graphics card (or that came wiith your pc), if not you can find one on the net for very cheap.
Depending on the age of your tv it might be best to just connect the two with a VGA cable. I have a very early HD TV and it just can't cope with the signal that I get from my PC, so I get a grainy picture like that when using an S-Video cable.
Hope thats not too much waffling ;o)