PoohBear is incorrect.
HDMI will pass a video and audio signal. If you only have a tv and dvd player, then plug the hdmi cable from the dvd player right into the tv. It will display the video signal as well as playback the audio signal into your tv's built-in speakers.
If you have a receiver and surround sound in the mix, it gets a little more complicated. Run the hdmi cable from your dvd player into the receivers hdmi input (this will deliver video and audio signals to the receiver). From here, the audio will be played back to your surround sound that you have connected to your receiver, so the audio part is done. As for video, that signal still needs to get to your tv! If your receiver has an hdmi output, connect an hdmi cable to the receiver's hdmi output and into your hdtv's hdmi input. If your receiver does NOT have an hdmi output, then you must utilize your receivers component output (every receiver should have this). Connect some component cables to your receiver's component output, and plug the other end into your hdtv's component input. The hdmi cable from your dvd player passes the audio and video signal to the receiver, plays the audio, and passes the video signal through component cables to your hdtv.
Hope that helps!