NextRadio uses your device's location to show a list of stations in your area. Some of your local stations may not be available because some stations don't stream, and some that do don't provide their stream to 3rd party apps like NextRadio.
You can also listen to stations that are outside your local area. To do this, tap the search icon at the bottom of the screen, and enter a station name, call letters, location or frequency. From the search results list, you can tap a station to begin listening, or tap the overflow icon (three dots) to the right and you can add the station to your favorites, making it easy to return to this station in the future.