Using a Sony Bravia HDTV as a monitor for a...

Question

What wires/adapters do I need to correctly do this. I currently have an adapter to have the Macbook Air output in DVI, and have that connected to the tv via a DVI-HDMI cable, however it only shows up on the tv as a picture, not a functional monitor. What do I need/How do I set it up so the tv actually works as a functional monitor?