I just started with MVVM so can anyone please explain and just show me baby steps on how I can switch windows using a button on a wpf please

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C#

//This is just to give an Idea what I want to do but in MVVM

private void btnLogin_Click(object sender, RoutedEventArgs e)
       {
           MainWindow mw = new MainWindow();
           mw.Show();
           this.Close();
       }

//I don't know anything on mvvm accept for what it stand for so please try to make it as simple as possible and step by step. Thanks a million