I have an iOS 5 pager application. Application can receive new message counter from server. For example application received 5 as a response from server. So no I need to create new (or update existing) notification in notification center panel and additionally I need the notification center to receive these notifications while the application is in background. Help me please. How can it be done?
All of the information you require is in Apple's iOS Developer docs: About Local Notifications and Push Notifications
You also might want to look into the introductory video from WWDC2011: Using local and push notifications on iOS and Mac OS X