You are going to have to look at your display prefrences and extend or have the duplicate screen on both the tv and the laptop. If you use duplicate then whatever you see happenign ont he laptop screen you will also see on the TV. If you have extended on then you may only see the desktop background on one of the screens. See if you can drag a picture or file or something from one screen to the other.
Also alot of tv's have a setting that you can set for to use it as a monitor. I think this only affects the color saturation or whatever but check that out as well.