How do I watch Netflix on my TV?

Check the back of your TV. If it does NOT have an available HDMI port, you can't do it with that TV.  Others have mentioned ROKU and Amazon Fire devices that you plug into the HDMI port--you'll need one of those. 

simple. run an hdmi cable from your computer to your tv

Get a Roku. It's a great smart TV platform.

Connect your mobile device to the same Wi-Fi network as your TV

Launch the Netflix app on both your TV and your mobile device

Sign in to the same Netflix account on both your TV and your mobile device

Select the Cast icon.

you have to pay to have it , get a roku box , you buy it , the subscribe on it per month . or most internet providers will connect you to netfix . reember netfix is not free , your used the download limit on the net plus a fee to connect with netfix .

Get a streaming device like a Roku.

Firestick, Chromecast are around £20-40 I think same in dollars.  Netflix is also available on appleTV, games consoles, some cable/satellite/freeview devices etc. You may also be abl;e to just connect a laptop easily via HDMI./

Basically netflix is on pretty much any device you can connect to a TV that supports video.

Buy a firestick.  

Try the HDMI from you laptop to the TV

Hook up one of these:

Roku

AppleTV

FireStick

XBox

Or does the TV have an HDMI in? And does your computer have an HDMI out? If so, you can get an HDMI cable, and hook your computer directly to the TV.