As a bonus if you’d rather host your own high score server and not rely on a cloud provider like Parse there is a free high score module from NovelGames that has ASP.NET and a PHP server side code. The PHP version uses MySQL for high score storage. The high score system is built for Adobe Flash but it just uses HTTP so you can easily adapt it to work with TRESTClient. Download the free server side high score system code here.
// PHP sample from loadScores.php
$siteID = $_POST['siteID'];
$gameID = $_POST['gameID'];
$gameName = $_POST['gameName'];
$playerScore = $_POST['playerScore'];
$playerCustomExtra = $_POST['playerCustomExtra'];
$playerID = $_POST['playerID'];
$playerName = $_POST['playerName'];
$playerEmail = $_POST['playerEmail'];
$playerUsername = $_POST['playerUsername'];
$playerPassword = $_POST['playerPassword'];
$playerPictureURL = $_POST['playerPictureURL'];
$playerFacebookUserID = $_POST['playerFacebookUserID'];
Head over and read the full tutorial about building a high score system using a cloud provider.