push notification in iphone..

Question

i want to implement push notification in iphone for client..i have googled it..and found these links..

http://mobiforge.com/developing/story/programming-apple-push-notification-services

http://blog.boxedice.com/2009/07/10/how-to-build-an-apple-push-notification-provider-server-tutorial/

is it i have to configure the client and servers..???

or the server will be configured by client ??

and how to configure the server..? have i to implement the code in the app??or i will update the server ..