Create Key binding in WPF

For your case best way used MVVM pattern

XAML:

<Window>
    <Window.InputBindings>
        <KeyBinding Command="{Binding SomeCommand}" Key="F5"/>
    </Window.InputBindings>
</Window>

Code behind:

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

In your view-model:

public class MyViewModel
{
    private ICommand someCommand;
    public ICommand SomeCommand
    {
        get
        {
            return someCommand 
                ?? (someCommand = new ActionCommand(() =>
                {
                    MessageBox.Show("SomeCommand");
                }));
        }
    }
}

Then you'll need an implementation of ICommand. This simple helpful class.

public class ActionCommand : ICommand
{
    private readonly Action _action;

    public ActionCommand(Action action)
    {
        _action = action;
    }

    public void Execute(object parameter)
    {
        _action();
    }

    public bool CanExecute(object parameter)
    {
        return true;
    }

    public event EventHandler CanExecuteChanged;
}   

For modifiers (key combinations):

<KeyBinding Command="{Binding SaveCommand}" Modifiers="Control" Key="S"/>