[iLinx]

http://php.net/manual/en/book.image.php
^how to create images with php

http://www.w3schools.com/PHP/php_ref_filesystem.asp
http://www.w3schools.com/PHP/php_ref_ftp.asp
^downloading files through ftp and reading files

http://www.w3schools.com/PHP/php_ref_mysql.asp
^using a mysql database (if your script is mysql based)

For user stats you will also need to understand the $_GET method unless you want to have a seperate php script for each user

If you just want a banner that displays server stats use -> http://game-monitor.com