Normally you have all the *Declarations* whether it be variables, functions, classes, structures, enumeration or any other type in the header. All the declarations normally go into the header function.

All the function definitions and all the other implementations go into the cpp file.

E.g .h file will contain :

Sample.h
class CSample
{
int m_iVar;

public:
int add (int iArg);
}

The above is the declaration of the class. It goes into the .h file.

Sample.cpp
int CSample::add (int iArg)
{
m_iVar += iArg;
return m_iVar;
}
The above is the implementation of the class. In our case, the class has only one function. So in the cpp file we just have the implementation of the member function.

But why do we have it this way. Why can''t we have it all in the same file. The reason is C++ is object oriented and you may want to build class hierarchies and sell it so that other developers who can extended or use them in their code. In this case, you need the developer, who is using your class hierarchy, to be able to see what functionality is in the class and you do not want him to see how you''ve implemented the various functionality. So, you build lib files for your class hierarchy and ship both the .h and .lib files to the developer. Now the developer can use your classes by including the .h file in his code but cannot see your implementation since he just has the .lib file and not the .cpp file.
DirectX SDK is a perfect example of this. If you look into the DX folders, you can see a bunch of .h files and .lib files.

Hope this is helps you to get started.
Happy learning C++. It is one of the most interesting languages I''ve come across.
Arun