Create CommandBindings in Xaml and bind to Button

   
  
<Window x:Class="Commands.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Commands" Height="300" Width="300">
    <Grid>
      <StackPanel>
        <StackPanel.CommandBindings>
          <CommandBinding Command="ApplicationCommands.Paste" Executed="InvokeApplicationCommand"/>
        </StackPanel.CommandBindings>
        <Button Command="ApplicationCommands.Paste">
          Paste Something (Control + V) when I have the focus!"
        </Button>
        
      </StackPanel>
      
    </Grid>
</Window>

//File:Window.xaml.cs
using System;
using System.Collections.Generic;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;


namespace Commands
{
    public partial class Window1 : System.Windows.Window
    {

        public Window1()
        {
            InitializeComponent();
        }

        void InvokeApplicationCommand(object target, ExecutedRoutedEventArgs args)
        {
            MessageBox.Show("The ApplicationCommand has been invoked.");
        }
    }
}