Using the “MyTuner Radio” app, there’s a progression of steps in the upper left hand corner. Here is a progression of pictures to show how to use it. Most Chromecast Audio users are familiar with these steps as they’re pretty much the same in most other audio streaming apps.

“These instructions assume you have a Chromecast Audio device turned on, connected to the internet, and set up in your location on the same network. Otherwise you won’t see any Chromecast icon.”