Many scripts or widgets that designers sometimes need to embed into their websites or blogs deal with communicating with Facebook. In order to do this, you would need to create a Facebook App ID. For example, adding a Facebook Members box to your website requires that you have an App ID. To get one, just follow the simple steps below.
1. Login to your Facebook account
2. Go to developers.facebook.com
4. Go to Create New App
5. Add the App Name, App Namespace, and App Category. Click on Continue to get the captcha screen.
6. After that, you should be able to see the basic settings screen for your new app. Congratulations :).
7. The most important things you need from here are the App ID and the App Secret. Most widgets that deal with Facebook require these two numbers, so copy them somewhere so that you can have them ready when you need them.