Asynchronous Programming in c# using async await

<Window x:Class="AsyncAwait.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="async/await - mkumaran.net" Height="255" Width="331">
 <StackPanel>
 <ListBox Name="lstBox" Height="200"/>
 <Button Name="btn" Content="Click" Click="btn_Click"/>
 </StackPanel>
</Window>

using System.Threading;
using System.Threading.Tasks;
using System.Windows;

namespace AsyncAwait
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void btn_Click(object sender, RoutedEventArgs e)
        {
            lstBox.Items.Add("Click()");
            Process1();
            lstBox.Items.Add("Click() - completed");
        }

        private async void Process1()
        {
            lstBox.Items.Add("Process1()");
            string result1 = await Process2();
            lstBox.Items.Add("Result - " + result1);
        }

        private async Task<string> Process2()
        {
            lstBox.Items.Add("Process2()");
            string result2 = await ProcessFinal();
            lstBox.Items.Add("Process2() - completed");
            return result2;
        }

        private async Task<string> ProcessFinal()
        {
            lstBox.Items.Add("ProcessFinal()");
            string val = string.Empty;
            await Task.Run(() =>
            {
                ////-----------------------------------
                ////------ Long running process -------
                ////-----------------------------------
                Thread.Sleep(5000);
                val = "mkumaran.net";
                ////-----------------------------------
                ////-----------------------------------
            });

            lstBox.Items.Add("ProcessFinal() - completed");
            return val;
        }
    }
}