Look on the back of the tv for a 'D' shaped connector with 15 pins marked 'PC IN'. This will allow you to view the laptop on the big screen. You will also need to run an audio cable between them if you want to hear sound.
The LAN ports are generally used to connect both items to a network or router, not to connect them together although it may be possible to use a crossover cable to do this if your laptop gets internet from a usb mobile internet device and you want to share it with the tv.