how to add in app purchases and ads

Ok so i recreated a unity game called wave and i changed it up to be my own but now i want to add in app purchases and ads. So the "Items" you collect should give you +5 coins and you can buy skins for the obstacles and the ball you move but i dont know how to do that, or make it so that when the player dies they can watch an ad that gives them an extra life

 

This should help https://docs.unity3d.com/Manual/IAPPromo.html . There is a sample IAP project here https://forum.unity.com/threads/sample-iap-project.529555/