Here's a great way to help people learn to use your mobile app. I'm implementing this in a new photos & camera app call Rainhut.
1. Build video How Tos by recording from the phone. Then use Screenflow or some other screen cast software to add callouts, popups and narration etc.
2. Host the vids on youtube.
3. Build a responsive web page and add your videos to the page. It needs to be responsive and ready for mobile use.
4. Wire your app the the responsive web page. Basically provide a help button to launch a browser inside you app and load the mobile web page of how to videos.
Here's my start. This page loads great inside my mobile app and the video play like I'm an expert and on boarding help. And the cool thing is I can add as many how to videos as I want without changing the app.
See Rainhut How To Videos Page