How to create a template class without errors in C++?

Question

I'm pretty new to C++ and I'm learning how to use templates. I made this simple code here with a template class to compare 2 "T" variable and return the highest value.

TemplateClass.h:

#pragma once

#include <iostream>
using namespace std;

template <class T>
class TemplateClass
{
    private:
        T a, b;

    public:

    TemplateClass() {}

    TemplateClass(T first, T second)
    {
        a = first; b = second;
    }

    T getMax();
    T getMin();
};

TemplateClass.cpp:

#include "TemplateClass.h"


template <class T>
inline T TemplateClass<T>::getMax()
{
    T result;
    result = a > b ? a : b;
    return result;
}

template <class T>
inline T TemplateClass<T>::getMin()
{
    T result;
    result = a < b ? a : b;
    return result;
}

When I'm calling the getMax method in my main.cpp, I get an error. (LNK2019 unresolved external error)

main.cpp:

int main() {
    TemplateClass<int> myobject(100, 75);
    cout << myobject.getMax();
    return 0;
}

When I put all my code in one cpp file (main.cpp for example), it works.