method for passing the keystrokes. You also need to track the textbox which is focused currently. First focus the proper textbox and then use the method to pass the keystrokes. It would be like a virtual keyboard thing (though not complete).
Get more information about it here
The solution for the same his available here
Please note that I have provided this as a sample only. In your application you may need something more than what I have provided. This is only for demonstration purposes.