"Unresolved external symbol" when using templates with CPP

Question

I wanted to create a generic array that could contain any type of data. The class looks like this GenericArray.h:

#pragma once
#include "LinkedList.h"

template<class T>
class GenericArray
{
public:
    GenericArray();
    void push(T to_push);

private:
    LinkedList<T>* _first;
};

And the implementation looks like this GenericArray.cpp:

#include "GenericArray.h"

template<class T>
GenericArray<T>::GenericArray() { this->_first = NULL; }

template<class T>
void GenericArray<T>::push(T to_push)
{
    LinkedList<T>* new_node = new LinkedList<T>(to_push);
    new_node->_next = NULL;
    if (this->_first == NULL)
    {
        this->_first = new_node;
        return ;
    }
    else
    {
        LinkedList<T>* last_nude = this->_first;
        while (current->_next != NULL)
        {
            current = current->_next;
        }
        last_nude->_next = new_node;
    }
}

But yet, when Im trying to build a file, I get this ERROR:

Severity Code Description Project File Line Suppression State Error LNK2019 unresolved external symbol "public: __thiscall GenericArray::GenericArray(void)" (??0?$GenericArray@H@@QAE@XZ) referenced in function _main Homework5 c:\Users\SSS\documents\visual studio 2017\Projects\Homework5\Homework5\main.obj 1

And:

Severity Code Description Project File Line Suppression State Error LNK2019 unresolved external symbol "public: void __thiscall GenericArray::push(int)" (?push@?$GenericArray@H@@QAEXH@Z) referenced in function _main Homework5 c:\Users\VVV\documents\visual studio 2017\Projects\Homework5\Homework5\main.obj 1

Obviously I did somthing wrong when using bad with templates. But I followed my code in order to find the problen, and I couldnt find anything suspicious.

If you can enlighten me, I will me gratful. Thanks.