It depends what you want out of the app.
If you want to own it and sell it:
Hire a programmer to program it. Make sure you at least make some simple wireframes so that it is clear what you want
If you just want it to be made:
find a dev that likes the idea and they will develop it. They will also own it.
So...decide. If you think this app can make some money (through ads or licensing), then just hire someone. Otherwise, I am sure a post in a few dev forums will find someone who is interested (so long as it is actually a good idea).
Note that if you find a dev who likes the idea and do not pay them, the timeline is on their schedule, whether they have real work or classes or something else that delays it. You have little to no right to complain, so that is something to think about, too.
Nkk
