I just bought this tv ( used ), because it says it is HD and 1080. However, when I got it home the picture is not that great. I just hooked the cable vfrom the wall to it and I do not have a box. I wanted to look in the manual to see if I need a box or something to get the HD quality picute. I have Brighthouse networks which offers free HD and I recieve it without a box on my newer Vizio LCD. So, how can I get a better picute on the Smasung?