I'm more familiar with XP and Win7, so..
Have you gone into the control panel and found the icon for the Display or the video? There should be an option somewhere, usually under Advanced, where there's a checkbox for "expand my desktop on this monitor". If that, in fact, is what you want to do.
Also, get the TV remote and be sure you're hitting the input button to cycle on to the HDMI input. With some LCD TV,s they may not take an HDMI output from a computer but may take a VGA or DVI output instead, which your laptop should have. I had a friend with a new RCA TV that would take the DVI/VGA output from a Mac Mini, but lose it upon restart. When we swapped the RCA with a Vizio TV, the signal was stable and he hasn't had any issues with it.