Easy.
If you mean just writing to a text file, you can use standard c++ calls to open the file, write the text, and then close the file.
If you want to write on a new notepad document, you need to use Windows API to open the notepad application, make sure it is in focus, and then emulate a keyboard sending the text from the recognition. You may even send the shortcut keys to save the file and exit the application if you want to.
