Let us quickly go through how do I add my distance, pace and duration using my ios app on my iPhone. It should work about the same way if you own an Android phone.
1) Sign in to your Nike+ app and tap on activity
2) Tap on the + icon on the top right corner of the screen
3) It will bring you to the screen below where everything is pretty straight forward
4) Manually set distance of your run
5) Manually set duration of your run
6) Manually set pace of your run
That's it, I wish I can manually key in my fuel too!