Check your TV and your Video Card documentation. You might not be able to do what you're trying to do. It's possible that the DVI output on the card is analog, which won't work with the HDMI (digital) input at the TV. The card may have an output type setting; if so set it to digital. If it doesn't, does the TV have a VGA (analog) input, if so use that. If not you may need to upgrade your video card to output HDMI or DVI-D, if your TV will allow you to connect a PC to the HDMI input.
Again check TV doc for resolutions and acceptable hook-ups for a PC.
Jeff