Open the Main Menu (left menu sidebar), select Apps, then select iHeartRadio.
You'll see an Activation Code screen. If you want to access the iHeartRadio app without an iHeartRadio account, click Maybe Later. If you want to log into your iHeartRadio account, open a web browser and go to iheart.com/activate. When prompted, enter the Activation Code displayed on your TV screen and your iHeartRadio account credentials.
You'll see a message that your iHeartRadio account is now activated on your device.
You'll be directed to the iHeartRadio app Home page. From here, you can listen to pre-selected stations, add your favorite stations, and search for stations, artists, and shows.
For more information, visit the iHeartRadio help site.