Send push notification from dot net code to firebase

using FirebaseAdmin;
using FirebaseAdmin.Messaging;
using Google.Apis.Auth.OAuth2;
using System;
using System.Threading.Tasks;

try
{
    var credentials = GoogleCredential.FromFile(Environment.GetEnvironmentVariable("GOOGLE_APPLICATION_CREDENTIALS"));

    var app = FirebaseApp.Create(new AppOptions
    {
        Credential = credentials,
    });

    var messaging = FirebaseMessaging.DefaultInstance;

    var registrationToken = "FCM registration token"; // Retrieve the token dynamically

    var message = new Message
    {
        Notification = new Notification
        {
            Title = "New message",
            Body = "You have a new message",
        },
        Token = registrationToken,
        Data =
        {
            ["key"] = "value",
        },
    };

    var response = await messaging.SendAsync(message);

    Console.WriteLine("Message sent successfully: " + response);
}
catch (Exception ex)
{
    Console.WriteLine($"An error occurred: {ex.Message}");
}

The code already uses await for the SendAsync method, but it's a good practice to use async and await throughout the code whenever possible. 

could you please share me full details by steb by step

Check the below example code that shows how to send push notifications from a .NET 6 application to Firebase Cloud Messaging (FCM) using the Firebase Admin SDK:

using FirebaseAdmin;
using FirebaseAdmin.Messaging;
using Google.Apis.Auth.OAuth2;
using System.Threading.Tasks;

var credential = GoogleCredential.FromFile("path/to/credentials.json");
var firebaseApp = FirebaseApp.Create(new AppOptions()
{
    Credential = credential,
});

var messaging = FirebaseMessaging.GetMessaging(firebaseApp);

var message = new Message()
{
    Notification = new Notification()
    {
        Title = "New message",
        Body = "You have a new message"
    },
    Token = "FCM registration token",
};

message.Data["key"] = "value";

var response = await messaging.SendAsync(message);