API - integration - solution - dog resuce

What Im looking to accomplish: Setting up the ability for WP users on their sites to easily post dog bios/info/photos that will also send back to Petfinder.com. I know it will push over to Facebook and Twitter but Im stumped on the API/feed back to petfinder. I have an API key, just not API savvy.

Q. Would one of the classified plugins work or what do you have for suggestions in that area?

My first website was a huge success for a dog rescue and many more are in the works and I want to get this streamlined. Thx in advance, Jeff.