merhaba arkadaşlar kullandığım db class aşağıdaki gibi

birde bu kullandığım sınıfın yapımcısı kim ve kullanma örneklerini nasıl bulurum?

$usersor=$db->prepare("SELECT * FROM kullanici where kullanici_id=:kullanici_id");
$usersor->execute(array(
	'kullanici_id' => $nick
));
$usercek=$usersor->fetch(PDO::FETCH_ASSOC);
$puan = ++$usercek['puan'];

yukarıdaki sorguyu aşağıdaki sınıf ile nasıl yapmam lazım?

class DB {
static $pdo = null;
static $charset = 'UTF8';
static $last_stmt = null;
public static function instance()
{
	return 
		self::$pdo == null ?
			self::init() :
			self::$pdo;
}
    public static function init()
    {
        $connection = 'mysql:host=' . MYSQL_HOST . ';dbname='.MYSQL_DB;
        $user = MYSQL_USER;
        $pass = MYSQL_PASS;

        try {
        self::$pdo = new PDO($connection,$user,$pass);
        self::$pdo->exec('SET NAMES `' . self::$charset . '`');
        self::$pdo->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_OBJ);
        }
        catch (PDOException $e) {
        die('Connection error');
        }

        return self::$pdo;
    }
public static function query($query, $bindings = null)
{
	if(is_null($bindings))
	{
		if(!self::$last_stmt = self::instance()->query($query))
			return false;
	}
	else
	{
		self::$last_stmt = self::prepare($query);
		if(!self::$last_stmt->execute($bindings))
			return false;
	}

	return self::$last_stmt;
}
public static function getVar($query, $bindings = null)
{
	if(!$stmt = self::query($query, $bindings))
		return false;

	return $stmt->fetchColumn();
}
public static function getRow($query, $bindings = null)
{
	if(!$stmt = self::query($query, $bindings))
		return false;

	return $stmt->fetch();
}
public static function get($query, $bindings = null)
{
	if(!$stmt = self::query($query, $bindings))
		return false;

	$result = array();

	foreach($stmt as $row)
		$result[] = $row;

	return $result;
}
public static function exec($query, $bindings = null)
{
	if(!$stmt = self::query($query, $bindings))
		return false;

	return $stmt->rowCount();
}
public static function insert($query, $bindings = null)
{
	if(!$stmt = self::query($query, $bindings))
		return false;

	return self::$pdo->lastInsertId();
}
public static function getLastError()
{
	$error_info = self::$last_stmt->errorInfo();

	if($error_info[0] == 00000)
		return false;

	return $error_info;
}
public static function __callStatic($name, $arguments)
{
	return call_user_func_array(
		array(self::instance(), $name),
		$arguments
	);
}
}