To install and use Nat Geo TV on FireStick, first, ensure your FireStick is connected to the internet. Then, from the home screen, navigate to the search icon and type "Nat Geo TV" using the on-screen keyboard. Select the Nat Geo TV app from the search results and click on it to download and install. Once installed, open the app and follow the on-screen instructions to sign in with your cable or satellite provider credentials. After signing in, you can browse through Nat Geo's extensive library of documentaries, series, and exclusive content, enjoying high-quality streaming right on your FireStick