If your TV doesn't have a wireless connection to the internet it will have a socket available on it to use a cable to connect it to your router.
If your router is a long way from your TV you need a pair of powerline adapters, something like these:
http://www.7dayshop.com/products/tp-link-200mbps-mini-powerline-ethernet-adapter-tl-pa211uk-twin-pack-S-TL-PA211UKX2
You plug one in near to your router and the other one near to your TV. An ethernet cable from your router to one and another from the other to your TV and you're in business.
You can also get the adapters with mains pass-through if you're short of electrical sockets near the TV or router.