With an active iAd Contract with Apple we're able to begin serving live iAd campaigns on a per-app basis. To enable ads, follow the ensuing steps:
1. Log in to iTunes Connect using your Apple ID. Select Manage Your Applications. Find and open the application you'd like to enable ads for.
2. From the right-hand menu, select Set Up iAd Network, as shown in the following screenshot:
3. Select whether your primary audience is for under 17 year olds. Apple currently doesn't deliver ads to apps targeted at minors. Click on the Enable iAd switch then click on Save.
4. Your app is now iAd enabled! Any future binaries you submit for this application will display live ads, once available in the App Store.