1st: is your tv capable of the same resolution as your laptop
2nd: Are you connecting via an HDMI cable or VGA?
if HDMI, then audio should be transmitted via the HDMI cable,
if using VGA, then you will need to use an audio cable from the laptop
(headphone jack, 3.5mm) to the TV's audio input jack(s) (RCA). This would be a 3.5mm to dual RCA ended cable
The tv does not need to be the same res as the laptop. Are you duplicating or extending? If it's duplicating and the laptop res is smaller, the tv will not be fullscreen. But the tv may have an option to stretch it to fullscreen. If you are extending, each display can be a different res. You could also try to set the tv as the main display.
More info may help. What are your specs or model number of the laptop?