Problem in window showing and hiding

Dear Sir,
i am new to opengl… nw i have created two opengl windows. one window was drawn first and the another is was coming from the first window button click. when the button is clicked second window was displayed and going behind of the first window… i cant show the second window in front of the first window… i dnt know that how to bring that second window in front of the first window, help me plz…

Thanks in advance…