How do I add Sling tv to my apple tv?

If you have a 4th generation Apple Tv, follow the steps here:

http://help.sling.com/articles/en_US/FAQ/How-do-I-install-Sling-TV-on-my-Apple-T V

If you have an older Apple Tv, you cannot install the Sling App on it.

If you have an Apple TV 4 you can look for the app on the App Store, I have no idea if there's a sling app or not. If you Ave an earlier Apple TV, you can't add apps.

Apps can be added only to Apple TV 4th generation. If you have ATV 4, log into the App Store on that device.