c++ how to put a pointer to a pointer in dvc

I'm new to c++ (java programmer) and I am working on a homework assignment for an intro course. The purpose is "Constructors, Dynamic Memory Allocation and Overloading Operators" That being said, I'm really stuck on one of the specifics.

I'm creating 2 classes Color, and ColorBox. It was specified in the instruction that the member variables in ColorBox are int width, int height and Color** data. My understanding is that data holds reference to a 2D array of Color objects...

My question is: How do I set some type of empty or basic value for data in the DVC? And does anybody have a link for a decent write up on this kind of pointer? I've found generic write ups on arrays and pointers but I'm still having trouble wrapping my head around this.

Thanks in advance!