If you connect the MacBook using a Mini-DVI to HDMI adapter you will probably need to use external speakers or a 3.5mm stereo headphone jack to RCA sound plugs connected to a stereo system for audio if your TV doesn't have separate RCA input plugs or a 3.5mm stereo input plug for audio with the HDMI plug. You attach it from the headphone jack of your MacBook to the appropriate audio input plugs.
The Mini-DVI to HDMI doesn't carry audio and there're no audio plugs on most TVs to work with HDMI since it's expecting audio with the HDMI. Check your TV manual though to see if it might have audio plugs that work with one of the HDMI ports. You attach it from the headphone jack of your MacBook to the appropriate audio input plugs on your TV.