Problems accessing private data members c++ - c++

Question

I have three files: Stack.cc, Stack.h and stacktest.cc . I am not sure about which files to include where, and i am getting different errors because of it. Currently, the code from Stack.h is:
#ifndef STACK_H
#define STACK_H
#include<iostream>
using namespace std;
template<typename T>
class Stack
{
public:
Stack();
void push(int);
void pop();
int top();
int size();
bool empty();
private:
class Element
{
public:
int data;
Element *next;
Element(Element *n, T d) : next{n}, data{d} {}
};
Element *first;
int num;
};
#endif
#include"Stack.cc"
the (relevant, i think) code from Stack.cc is:
#include<iostream>
using namespace std;
template<typename T>
Stack<T>::Stack()
{
first=nullptr;
}
template<typename T>
void Stack<T>::push(int)
{
num++;
first = new Element(first, data);
}
Stacktest is currently just a test file attempting to call the default constructor. The errors i currently get are:
In file included from Stack.h:30:0,
from stacktest.cc:2:
Stack.cc: In member function ‘void Stack<T>::push(int)’:
Stack.cc:22:28: error: ‘data’ was not declared in this scope
first = new Element(first, data);
^
Stack.cc: In function ‘int size()’:
Stack.cc:62:11: error: ‘num’ was not declared in this scope
return num;
For some reason it wont let me access private data members. Before i didnt have the include in the .h file and instead included the .h in Stack.cc, and that worked, although wouldnt let me access the stack class from Stacktest.cc(Stacktest.cc just includes Stack.h)
Any help would be greatly appreciated, thanks.