If you are not a programmer, then put as much work as you can into sketching out and documenting how exactly you would envision or want this app to work.
Think about what a consumer or a person using the app would behave, and what he or she would want to do in the app. Put yourself in their shoes, and then write it out step by step. This is called use-case scenarios. Your app might have multiple use-cases. Think about ways your app users would use it that you might not have thought about.
Once you've written it down, make sure you also do the work of drawing or sketching each and every possible screen. If you have photoshop and know how to use it, consider buying a bootstrap app design from sites like ThemeForest (http://graphicriver.net/?ref=jmsierra). Do a search for bootstrap App UI. These can easily be modified to show/illustrate what your app would look like and how it would work at its most basic form.
Two final steps:
1) There are various tools available that allow you to create animated prototypes of an app. This means you can click through, and experience what the user might experience, without having to code (and of course, key technical functionality would not work). Use your sketches or photoshoped graphics to create a working prototype. This will allow you to test it and show it to potential users that can give you feedback.
2) Hire a programmer to code it for you. This is the harder and more expensive part. You can try to find a good app programmers viva websites like oDesk.com. The challenge here is that you need to vet and interview potential programmers as you would a new employee or hire. Assuming you don't have a lot of experience with that, it can be challenging (and expensive on the long run).
Or, if you know an app programmer in person, you can try to hire or contract out.
One last idea or suggestion -- once you have documented and sketched out your idea in detail, it could be a lot easier for you to potentially seek out a partner or investor willing to fund the development of your app. Before you take this path, you'll want to do some of the business research -- what are competing apps, are there other apps doing similar things, how much demand do you think there can be for your app, etc?
The main thing I would say to you right now -- continue fostering that creativity. Whether this app gets developed or not, sharpen those innovation skills by looking for problems around you and thinking about ways to solve them.