First, I recommend you to get a newer version of MySQL. 2.23.36 is too old, or is it a typo??? 3.23.36 is acceptable.
Anyway, start Xitami, open your browser, go to http://localhost/admin/
Go to configuration, click Filters.
Add the following:
.php c:/path/to/php.exe
.php3 c:/path/to/php.exe
You're done!
To use MySQL, simply start mysqld-opt.exe. Create a new php script, and use mysql_connect('localhost'); mysql_select_db('anydb');
For more information about MySQL see the manual (http://www.mysql.com/doc), and the PHP-manual (http://www.php.net/myslq), or read a tutorial about it on PHPBuilder.com.