There are basically three ways to connect the internet to a Smart TV. These ways include;
The first way is the wireless option. Presently most of the Smart TVs are Wi-Fi enabled, so there you will get the support of a built-in wireless adapter. With the built-in adapter, you can easily connect the TV with the internet.
The second way is to directly plug the TV to the internet router by an Ethernet cable.
The third way is to use a powerline to connect the TV to the internet. If your TV is installed in another room from the router, you can use a powerline kit to connect the TV to the internet.