<?php
$mysql_server = 'localhost';
$mysql_username = 'user';
$mysql_password = 'password';
$mysql_database = 'database';
$mysql_table = 'table';
$success_page = './Profile.php';
$username = 'username';

$db = mysql_connect($mysql_server, $mysql_username, $mysql_password);
      if (!$db)
      {
         die('Failed to connect to database server!<br>'.mysql_error());
      }
      mysql_select_db($mysql_database, $db) or die('Failed to select database<br>'.mysql_error());

$sql = "UPDATE `".$mysql_table."` SET `Credit` = `Credit` + 5 WHERE `username` = '".$username."'";
mysql_query($sql, $db);

header('Location: '.$success_page);
exit;
?>