iOS 9.3 is coming in the Spring and will introduce Night Shift as well as a number of other new features.
Apple Posts Step-by-Step Guide to Activating 3G Service on iPad Wi-Fi + 3G
The guide provides a series of screenshots to show users the exact process for activating 3G service on their new iPads, from adding contact information and creating a login account to selecting a data plan and entering payment information.
The process also includes a review of the Terms of Service for AT&T, and upon agreement with the terms, displays a payment summary for the activated plan. International data can also be managed through this screen and must be added before leaving the United States.
Once completing the signup process, it may take several minutes for 3G service to be activated, but customers can use their iPad as normal on Wi-Fi and will be notified by an alert once the plan is activated.