Need Help in Creating PHP/MySql API for my Application

Question

Hi Friends,

I have developed an Application in PHP/MySql Technology

Now I want to develop an API for that Application

I have Created the first step Request XML and i send that XML via cURL

but now what i have to do after that the server Setup and response XML both of them i wont able to create.

So kindly help me to build my API.

Thanks in Advanced