writing a map as template with Pair and iterator c++ - c++

Question

A little help please with this task, I need to write a simplified map template with Pair class and iterator class, I'm a beginner and I'm really messy and troubled with this, I would be glad for some help only with the header.
#include <cassert>
#include <functional>
#include "Exceptions.h"
template <typename DataType>
struct Node {
DataType data;
Node<DataType> *next;
};
namespace mtm {
template <class KeyType, class ValueType, class CompareFunction = std::less<KeyType> >
class MtmMap {
public:
class Pair {
public:
Pair(const KeyType& key, const ValueType& value)
: first(key), second(value){}
const KeyType first;
ValueType second;
~Pair() = default;
Pair* begin();
Pair* end();
void insert();
void insert(const KeyType&, const ValueType&);
void remove(const KeyType&);
bool containsKey(const KeyType& key) const;
int size() const;
Pair& operator=(const Pair&) = default;
ValueType& operator[](const KeyType&);
const ValueType& operator[](const KeyType&) const;
Pair& operator[]();
/*private:
Node<Pair> _pairs;
int _size;
*/
};
class iterator{
/*private:
Pair *cur_itr;
Node<Pair*> pair_ptr;
*/
public:
iterator();
iterator(const Pair*);
iterator(const iterator&);
~iterator();
iterator& operator=(const iterator&) = default;
iterator& operator++(int);
iterator& operator++();
iterator& operator*();
bool operator==(const iterator&);
};
bool operator!=(const iterator&, const iterator&);
};
}
I was given an empty part, like this:
#include <cassert>
#include <functional>
#include "Exceptions.h"
namespace mtm {
template <class KeyType, class ValueType, class CompareFunction = std::less<KeyType> >
class MtmMap {
public:
class Pair {
public:
Pair(const KeyType& key, const ValueType& value)
: first(key), second(value) {}
const KeyType first;
ValueType second;
};
};
}
And the first part is after I wrote all the needed for realization operators and functions. Notice that it is pretty simplified version of map container, so I only need this part, WITHOUT USING ANY STL.
Can somebody help with writing the private fields and other things that belongs to the structure of the template class MtmMap ???
The idea using a list struct is mine, as I need list of operators and pairs as a container, as I can see it.
Any other ideas, comments, and stuff will be excellent and I'll be grateful, thanks a lot.
EDIT:
Just to clarify my question, before I'll continue to the cpp file for realization, I'm stuck, because I don't understand how I should realize all the functions of the map, how to storage them and etc.
I need help finishing this header.