Need Ad Mob added to Android App(repost)

I have an android application that is currently on the market as a pay-for app and I would like to add Ad-Mob and Grey Stripe support where when the app is started up there will be a full screen add that has to play first and then it will allow users to use the application so that I can market a free version. The app was made in app-inventor. I need the Admob and Greystripe up and running.