Hello guys.. I'm working on a project. There are 3 classes. Two are inherited from one.
This is the implementation of the main class. There's an error. I have no idea how to debug it.
Would you please check it?!

# include <iostream>
# include <string>
# include "MainMenu.h"
using namespace std;

MainMenu::MainMenu()
{
destanation="no destanation yet.";
departure="no departure yet.";
date="no date entered yet.";
time="no time yet.";
}

MainMenu::MainMenu(string the_name)
{
name="No name yet.";
}

MainMenu::MainMenu(string the_destanation, string the_departure, string the_date, string the_time)
{
destanation=the_destanation;
departure=the_departure;
date=the_date;
time=the_time;
}

ostream& operator << (ostream& outs,const MainMenu& settings)
{
	outs<<settings.departure
		<<settings.destanation 
		<<settings.date
		<<settings.time;
return outs;

}

istream& operator >> (istream& ins,const MainMenu& settings)
{
	ins >>settings.departure
		>>settings.destanation;
return ins;
}

void display_main_menu ()
{

cout<<"Hello and welcome to J-Otaku-Air travel agency."<<endl
		<<"Please choose a number from the following menu, then press enter to "
		<<"move to the desired page."<<endl<<endl
		<<"1. About J-Otaku-Air"<<endl
		<<"2. Reservations"<<endl
		<<"3. Currency Converter"<<endl
		<<"4. Budget Travels & Special Offers"<<endl
		<<"5. Frequently asked questions"<<endl
		<<"6. Contact us"<<endl
		<<"* Press 0 to exit"<<endl<<endl;

}

string MainMenu::choose_from_main_menu (string choice)
{
cin>>choice;
return choice;
}

void MainMenu::JOTAKU_LOGO () const
{
		cout << "\t\t\t =================    "<<endl;
		cout << "\t\t\t     ||   || || ||    "<<endl;
		cout << "\t\t\t     ||   || || ||    "<<endl;
		cout << "\t\t\t     ||      || ||    "<<endl;
		cout << "\t\t\t \\   ||         ||   "<<endl;
		cout << "\t\t\t  \\  ||              "<<endl;
		cout << "\t\t\t   \\ ||              "<<endl;
		cout << "\t\t\t    \\||  J-Otaku-Air "<<endl;
		cout <<endl;
		cout <<endl;
}

This is the compilation message.
1>------ Build started: Project: cs102 proj, Configuration: Debug Win32 ------
1>Linking...
1>MSVCRTD.lib(crtexe.obj) : error LNK2019: unresolved external symbol _main referenced in function ___tmainCRTStartup
1>C:\Users\fofa\Documents\Visual Studio 2005\Projects\cs102 proj\Debug\cs102 proj.exe : fatal error LNK1120: 1 unresolved externals
1>Build log was saved at "file://c:\Users\fofa\Documents\Visual Studio 2005\Projects\cs102 proj\Debug\BuildLog.htm"
1>cs102 proj - 2 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

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