Pass additional operation to a function hook in windows

Hi, I have been doing this to learn the windows internals and there's was the hook api click menu notepad thing I learned from http://diendan.congdongcviet.com/threads/t26558::hook-message-click-button-menu-tren-process-khac.cpp but here, I want to perform following things:-
Open file by

File -> New File in Notepad

But I don't seem to do so, anyone how this could be possible?
Thanks