You're not getting the second window opening because instead of sending generateWindow to the secondWindow instance you set up in the XIB, you create a new one in openNewWindowAppDelegate's openWindowButton method and send generateWindow to that.
This new instance isn't the one who's secondInfoWindow outlet is connect to the 2nd window in your MainMenu.xib. You'll find that this outlet is in fact nil for this new instance because you never it set to be anything else. It's the separate and different instance of secondWindow in your XIB who's outlet has been connected.
With this kind of arrangement, you'll need to connect the secondWindow instance in your XIB to an outlet in openNewWindowAppDelegate so that openNewWindowAppDelegate's openWindowButton can send generateWindow to correct instance of secondWindow.
And please name your apps and classes with initial capital letters.