Connect with Facebookbutton. I am using Spring social api for Facebook functionality.
You have to enter your mobile phone and get a confirmation code to create a Facebook app from https://developers.facebook.com/ Apps tab. Unfortunately, this was a bit problematic for me, i waited more than an hour to get a confirmation code with sms. After creating a Facebook app, you obtain an app id and app secret. They are important for your application to run successfully. Moreover, in development mode, do not enter any app domain, but add your localhost address as a canvas url as explained in http://stackoverflow.com/questions/4532721/facebook-development-in-localhost.
Now, with the help of the app id and app secret, you are able to write your application..
Facebook changed policy this month. The default Graph Api version is 1.0 for Facebook apps created before this month and 2.0 for apps created in this month. The facebook issues are summarized in http://www.nextscripts.com/known-issues/facebook-issues/