Create an empty game object and attach the AdMobBannerInterstitial script. It will cause a scene with this game object, show interstitial ads in few seconds after the scene is loaded.
Create an empty game object and attach the AdMobBanner script. You can also fill the banner settings as on the screenshot below. The resulting scene with this game object will contain banner ad according to the script settings.
The example can be found on the NoCodingExample example scene.