You basically have to register your application in the Windows store, and then register it in the notification service. The explanation is quite extensive, but do not worry, you can see step by step how to do it by leaning on Azure and its notification center from the following link:
link
This is for UWP in native. However, you can find the same information to configure the service with Xamarin.Forms, Android, iOS, Amazon ...
Important. You have to be registered as a developer in stores to be able to register applications and send push notifications.