Phone plays last song in Music app instead of one in iReal Pro -SOLVED

New to iPhones AND iReal Pro. Really an iPhone 5 question but crucial to playing iReal Pro.

I Installed iReal Pro on new iPhone 5C (iOS 7), and started playing exercises that come with it. Worked perfectly. Can't wait to utilize it.
THEN, I imported some song files into my phone from my computer iTunes, and also opened an iTunes radio station. Now, when I try to play an exercise, the control panel is loaded with the last song I was listening to in radio or my playlist instead.

I tried stopping the phone's music app by double-clicking the Home Button, which shows all running apps. The method for stopping an app is to touch the page and slide up, which carries the page away, signifying closing the app. I did that, and the music app page or its icon is no longer there, but the control panel still shows and plays the last song instead of the exercise. Can't find iPhone support explanation anywhere. What am I missing for -Oh. just realized: you don't slide up the phone's control panel; you tap the screen to bring up iReal Pro's own control panel. (Either dementia or new information overload)

Run a Search in iBooks (if you do not have it, download it from the App Store, it is free) for 'iPhone user manual for iOS7' (which is free also). You will find it useful for understanding your iPhone in general.