I need some resources, examples, or tutorials to be able to understand how to write a server in PHP which can communicate with MySQL database, and receive & send the desired information to the client from the database. If you offer some websites or books, I would appreciate.
When you say 'write a server' I assume you aren't talking about creating a web server using PHP? (Which would be impossible).
Once you have the basics of MySQL_* you can begin moving onto the newer extension which is MySQLi(mproved) which has more security benefits.
Don't forget the official resources, such as PHP.net.