How can I create my own mobile app?

Before you start worrying about how you want to build your own mobile app, you should have answers to these questions: what problem are you trying to solve? What do you want your app to do? Have you sketched out your idea? If you have answered them then you can proceed.

To build your own mobile app is easy. There are many app building programs on the internet today.
After you have sketched your idea, use a wireframing website that will give you a board on how your app will function, this will help bring your idea to digital life. Use sites like:axure.com and adobe.

Then use a service that can provide hosting and collecting data about your app. Use services like: parse.com,applicasa.com.
Get beta testers to test your app.

If you find the process challenging, you can hire a mobile app developer to do all the background work like - server, databases and API.