Using your handheld iOS device, you can stream any music app you choose. You can also stream iTunes® from a Mac® or PC. The music app or program in use is where you will find the AirPlay icon.
Locating the AirPlay® icon when playing music apps (video included)
Tap or click the icon to choose your speaker source. The AirPlay icon is usually found at the top or the bottom of the app or program in use, such as iTunes, Pandora® and YouTube.