i have a game i need a main menu how do i make one?
Perhaps you can refine your request a bit. What exactly are you looking for in a main menu?
To get you started, look up how to use GUI Textures along with OnMouseEnter/OnMouseExit, OnMouseDown/OnMouseUp, etc. Using GUI Textures and those functions you can create basic menu items with rollover events and responding to mouse clicks.
If you need more help than that just refine the question a bit, good luck!