How to add interstitial ad to you android app?
This tutorial shows how to create and get an ID for Interstitial ad.
Log in or sign up https://www.google.com/admob
Select You Project and select "Ad units" (1). Click button "Add ad unit" (2)
Click -> "Select" (1) under Interstitial block
Enter you "Ad unit name" (1) and click -> "Create ad unit" (2)
Copy ad unit id (2) and click -> "Done"
Paste you interstitial ad unit id to you strings.xml (Android App) file, constant "interstitial_ad_unit_id"