hi,
well first of all you should have something already or it should be such an amazing project that good programmers would come and code for you. there are a lot of good projects out there so if you don't have anything solid i doubt a good coder will give your project a try.
better thing you can do is find some friends who can code (in your school or wherever) and start of like that. brainstorming and coding together. after having your beta 0.000001 and you publish it (e.g on source forge), you might find more interest from pro coders online, if it is a good project.
good luck,
hope to hear from your project one day