If you are using Android you just need to learn how to programme in Android Studio. Creating a high Graphic Processing application may be very hard but once you know how to code it'll be easy. You can use MIT university's software- App Inventor(If you think Android Studio is hard :P) And if your using iOS (i.e. iPhone or iPad) you'll need to learn 'Objective C' or 'Swift', there is no 'easy' way to make apps in iOS.
Happy Programming,
Prajwal