How can i access my second class through the Main function?

I have created two classes (Konto and Bank). I can access my first class (konto) through the main function but I can not access my second class (Bank) in order to set/change its values.

One of my friends told my that the problem is that I have my code in subfolders but I really do not know what it is and how I delete it.

So how can I access my second class(Bank) is my question.

#include <iostream>
#include <string>
#include <vector>

class Konto {
public:
  int konto_nummer;
  std::string agare;
  double saldo;
  double rantesats;

public:
  Konto(int _nummer, std::string _agare, double _saldo, double _rantesats);
  int ge_konto_nummer();
  void ranteutbetalning(double r);
  //~konto();
  friend class Bank;
};

class Bank {
private:
  std::vector<Konto> konton;
  int antal_konton;
  int bank();

public:
  Bank(std::vector<Konto> _konton, int _antal_konton);
  void skrivut();
  //~Bank();
};

Bank::Bank(std::vector<Konto> _konton, int _antal_konton)
    : konton{_konton}, antal_konton{_antal_konton} {}

Konto::Konto(int _nummer = 12345, std::string _agare = "Ali",
             double _saldo = 500, double _rantesats = 0.07)
    : konto_nummer{_nummer}, agare{_agare}, saldo{_saldo}, rantesats{
                                                               _rantesats} {}

int Konto::ge_konto_nummer() { return konto_nummer; }

void Konto::ranteutbetalning(double r = 0.07) {
  rantesats = r;
  saldo += (rantesats * saldo);
}

void Bank::skrivut() {
  int choose;
  std::cout << "Choose: " << std::endl;
  std::cout << "1- Adda new account: " << std::endl;
  std::cout << "2-Print ur accounts: " << std::endl;
  std::cout << "3- Search for accounts: " << std::endl;
  std::cout << "4-Avsluta" << std::endl;
  std::cin >> choose;
}

int main() {
  Konto person;
  std::cout << "Account: " << person.konto_nummer << std::endl;
  std::cout << "Owner: " << person.agare << std::endl;
  std::cout << "saldo: " << person.saldo << std::endl;
  std::cout << "Rantesats: " << person.rantesats << std::endl;
  std::cout << "===============================" << std::endl;

  Bank obj;
  obj.skrivut();
}