I liked the content of your tutorial.

• It's easy to understand
• Your diagram is eye catchy, nice color
• Most of the code is explained

However, I have some few advice for this tutorials to make it readable:

• zoom the screenshotted code
• for long code, try to break it down
• avoid starting code with long space or tab like:

                     CREATE TABLE `users` (
                     `id` int(11) PRIMARY KEY NOT NULL AUTO_INCREMENT,
                     `username` varchar(255) NOT NULL,
                     `password` varchar(255) NOT NULL
                   ) ENGINE=InnoDB DEFAULT CHARSET=latin1;