window size

I set my window’s size according to the screen resolution . Is there any way when the window starts to be maximized ?

for windows:

ShowWindow(hWnd, SW_SHOW_MAXIMIZED);

See lesson 1 of the NeHe articles:
You can press the F1 key to switch between the fullscreen and window modes.You can download the source code and use from it to write your OpenGL programs.