#1- you have to enable the GD/2 Library In your php.ini file... other wize.. any function you try to call that uses the gd library will return an error.
#2- It is rather simple.. ill like you to a site for an example but it can be easily modified to do what you want...
http://www.acecoolco.com
go to tutorials > PHP > GD
then it will be listed there
(yea i beat ya to your own site acecool
)
you can even go here for MORE (alot more) about GD
http://ca.php.net/manual/en/ref.image.php
if you need help, you can contact me using AIM or MSN using my contact info below.