Global Class Decleration

Hi,

I am using uVision4 for LPC3250.

I declare my class in my header file and define its functions in the corresponding cpp file.

My question is this, how can I reach the object of this class when I create it in another file.

For example, in a.cpp:

MyClass MyObject;

in b.cpp

MyBoject.value = 5;

I want my object to be global.

Thanks for your helps.