Highscores list for facebook app

Question

Hello i have a small app on facebook called typepractice (url) and im trying to do a highscore system. I store the score in a scores object and save its id and user id in users object, like this:

// setting score
$scoreID = $facebook->api_client->data_createObject("scores", array("score" => 100) );
$userID = $facebook->api_client->data_createObject("users", array("userid" => $user) );
$facebook->api_client->data_removeHashKey("users",md5($user));
$hash = $facebook->api_client->data_setHashValue("users",md5($user),$scoreID,"scoreid");

// reading score
$query="SELECT score FROM app.scores WHERE _id = ".$facebook->api_client->data_getHashValue('users',md5($user),'scoreid');
$result = $facebook->api_client->fql_query($query); 

I need to build a list of 10 friend and their scores and list of 10 users of the app and ther score. Is that posibble? The documentation is really confusing.