数据绑定，以便更改TextBox值更新LIstBox

我试图让数据更新进出XAML。 即，当我在XAML TextBox中进行更改时，C＃将接收新值，当我更改C＃（通过单击按钮模拟）时，XAML TextBox都会更改。 我有这个工作，但是如果我对XAML TextBox进行更改，它会更新XAML ItemsList。 任何想法我怎么能这样工作？

MainWindow.xaml …

MainWindow.xaml.cs

 public class Person : INotifyPropertyChanged { public event PropertyChangedEventHandler PropertyChanged; private String _FirstName; public string FirstName { get { return _FirstName; } set { _FirstName = value; if (PropertyChanged != null) PropertyChanged( this, new PropertyChangedEventArgs("FirstName")); } } public int Age { get; set; } } public partial class MainWindow : Window { public Person[] people; public MainWindow() { InitializeComponent(); people = new Person[]{ new Person{ FirstName = "Shirley", Age = 22 }, new Person{ FirstName = "Roy", Age = 29 }, new Person{ FirstName = "Manuel", Age = 34 } }; StackPanel1.DataContext = people[0]; listPeople.ItemsSource = people; } private void Button1_Click(object sender, RoutedEventArgs e) { people[0].FirstName += "y"; } }