I would obviously pay them if/once the idea took off, but I don't have the capital to do so now.
Simple answer is you will never find someone who will work for free. The old saying, "Money for nothing and your social media idea for free".
Either get good at coding, or partner, I use that term loosely, with someone who can. A partner does not have to own 50% of something, they can own 1-99% of it and still be a contributor. There are freelance sites out there where you can post your project up and potential candidates will bid on the project. Who knows, maybe you can find someone who can code your idea for a few hundred dollars. If you believe that it will be successful then that should not be a problem.
Search for venture capitalists, only problem will be the ownership requirements for some may make you the minority owner. Best of luck.