A few quick pointers:
if($submit)
Here you use a variable which relies on register_globals being on, yet later you use code which assumes it is off. You should choose one or the other (the latter being preferred). This occurs in quite a few places.
if(!$title){ //this means If the title is really empty.
That actually checks whether or not $title is a set variable. empty() can be used to check whether a (set) variable contains a value. PHP can be set to throw warnings if you try to use an unset variable (which you are doing).
You also don't check the form inputs before inserting them into the database. That basically leaves the script wide open for nasty things like SQL injections and XSS attacks.
For a slightly nicer output you could format the date field, with PHP's date() or MySQL's DATE_FORMAT().
It might be worth using PHP's functions instead of MySQL's, to make the code more portable. But you've stated it's a PHP/MySQL tutorial, so tell me to shut up if you want 😉
Overall, a well explained starter tutorial. A few fixes and it would be a good primer for somebody.
