How does one create a class that uses the elements of a structure as its elements?

In specific, I have a structure that contains a number of elements, that I need to be able to use without changing the structure. However I also want to use the elements of the structure and serialize it and ultimately I want to phase out the structure, therefore I would like to be able to substititute a class wherever the structure is required.

This type of approach is taken by the CRect class and Rect Structure and the CPoint class and Point structure. Could someone please explain how the elements of the structure were made public elements of the class. Any help is appreciated.

Thanks