loop in menu

guys, I need my program to repeat itself again after we do any step.EX Once I run my program the menu will pops up, I will press 1 and I will enter the code than I need the menu to pops up again without running the program again. I don't know how to use the while loop?

Code:

#include <iostream>
#include <cctype>
#include<string>
using namespace std;

void newCode();
 void printCode();		

int main()
{
	int tester;
			cout << "select one of these options\n";
 			cout << "(1) Insert a new code\n";
 			cout << "(2) Print the data\n";
 			cout << "(3) Exit the program\n";
			cin >> tester;
	
	
		if(tester==1)
			newCode();		
		else if (tester==2)
			printCode();
	/*	else if (tester==3)
		
		else
			cout << "ERROR!!! You must choose one of the options from 1 to 3";*/
   	
  	return 0;
}  

void newCode()
{
	string serial_number;
	int length;	
	
   cout<< "please enter a serial number of 12 characters:";
	cin >> serial_number;
	length = serial_number.length();

	if (length!=12 )
		cout << "The code you have entered cannot be processed because the code must 12 characters exactly";
	else 
		cout << "The serial number is:/n/" << serial_number;
}	

 
 void printCode()
 {
 	string serial_number;
 	cout<< serial_number;
 }

Code:

int tester = 99;
while(tester != 3)
{
 
}

Just put your menu between the brackets. It will continue to run untill "tester" equals "3", which is your option to exit the program. Make sure you give tester a value before you use it in the while loop (any number will do as long as it isn't 3).

Edit*
You could also use a do while loop:

Code:

do
{

}while(tester != 3);

and you wouldn't have to assign "tester" a value.