Question

I have created a Facebook application. Now I would like to see the details of the users of my app (I mean authenticated Facebook users). And I would like to post some thing to the first 5 users (older users). How can I do this?

Answer 1

Assuming that you have authenticated the user with the permissions to get his detail. You can then call the Facebook Graph API method.
For javascript:-

FB.api('/me',function(response){
   //Write you code to access the response object returned like
alert(me.name);
});

Or you can use PHP SDK and use its method after initializing it with the required permissions

$result = $facebook->api('/me','GET');

The result object is an array that stores user information.

Regarding the last part of your question you have to implement some sort of counter and do the post using the same api method call.