Facebook Applications are essentially designed to give a custom look to the website and facilitate to attract the attention of Facebook browsers. Though sometimes complicated, they are generally used as add-ons to other software programs or devices to work. The passionately popular Facebook social networking platform has issued an open Application Programming Interface (API) and developers are drinking it up to create applications and new features for Facebook. To work with the data from Facebook, all the third-party systems can make use of this API, which is a combination of OAuth 2.0, REST-style techniques and a mixture of web technologies and are collectively titled as the Graph API.
Developing Facebook application is a pretty difficult task as it requires innovative skills with various other things which are different from developing the custom applications. If you are interested in creating, configuring and developing your own application on the Facebook platform, you should be ready to go through a lengthy process. It is inclusive of technical and non-technical skills and requires smart knowledge in Facebook Markup Language (FBML), and Facebook Query Language (FQL). Moreover, it involves utilization of community-supported wiki and bug tracker and helps to combine the automated and scheduled works. Developers who are unaware of social networking and its depth on the Internet may find it hard to develop alluring applications. Such people can make use of the Facebook application development platforms and techniques to create their own Facebook applications.
Here are the links for you to start:
Download/learn Facebook SDK: https://developers.facebook.com/
Facebook and Flash: http://code.google.com/p/facebook-actionscript-api/ ; http://www.adobe.com/devnet/facebook.html