TV only displays background image from macbook air over HDMI connection?

I bought an HDMI adapter form the apple store today and connected my macbook air to my 60 inch Vizio LED TV. When i do this all the TV screen displays is the background image that is on my macbook. Absolutely nothing else from the desktop shows up. If I open an app it doesnt show up on screen. The icons on my desktop dont show up and none of the menu bars. Does anyone have any idea what I need to do to fix this?

Addendum: I found the solution in the display settings. I had to go to the Arrangments tab and then click Mirror Display but now there doesnt appear to be any sound. Any ideas how to fix that?