How do i bring one GUI window in front of another?

I have two windows, one of which when loaded always goes behind the other. How do i make it so the first one goes in front of the second one?

GUI.FocusWindow(0);

^ the (0) is declared when you do the OnGui()

EG:
windowRect = GUI.Window (0, windowRect, DoMyFirstWindow, “First”);

its the number just after the first bracket

Hope this helped