To begin using Tv.youtube.com/start, simply open a web browser on your computer or mobile device and navigate to the specified URL. Once there, you'll be prompted to sign in to your YouTube TV account or create a new one if you don't already have an account. Follow the on-screen instructions to complete the sign-in process. After signing in, you may need to enter the activation code displayed on your TV screen to link your device to your Tv.youtube.com start. Once confirmed, you'll have access to live TV, on-demand content, and personalized recommendations on your TV screen through the YouTube TV platform.