What do u need to start an API ?

To get up and running with developing an online Facebook application, you need to have three things in place:

1. A valid Facebook account
2. Access to a web server running a supported middleware language
3. The client library for your particular middleware language.

If you’re working on a desktop application, you still need a Facebook account (for authentication), but you will need only the client library for your language because your interactions with the Facebook servers will be handled by your program and not a web server.