To send a notification with Firebase, you have to go to your project and Select Cloud Messaging.
The steps are very simple:
1)
2)
Then click on New notification:
3)
We need to type the information and click next:
4)
You will need to select the app on the menu and click Next.
5)
You can select when to send the notification. Then click Next.
6)
¡Click publish and we are done!