Your Apple TV can connect to WiFi. So if you want to watch Netflix, you need to register first (easiest to register on Netflix website on PC) . If you don’t have an Apple ID yet, you need to register for one too.
Then plug in your Apple TV and connect it to your tv and use the menu to sign in with your Apple ID. You also connect it to your WiFi network. Then you go to the Netflix app and then login and should work.
It sounds daunting but the menu is very easy to work with