how to add system.messaging c#

                                    using System;
using System.Messaging;

namespace MyProject
{
    /// <summary>
    /// Provides a container class for the example.
    /// </summary>
    public class MyNewQueue
    {

        //**************************************************
        // Provides an entry point into the application.
        //		 
        // This example demonstrates several ways to set
        // a queue's path.
        //**************************************************

        public static void Main()
        {
            // Create a new instance of the class.
            MyNewQueue myNewQueue = new MyNewQueue();

            myNewQueue.SendPublic();
            myNewQueue.SendPrivate();
            myNewQueue.SendByLabel();
            myNewQueue.SendByFormatName();
            myNewQueue.MonitorComputerJournal();
            myNewQueue.MonitorQueueJournal();
            myNewQueue.MonitorDeadLetter();
            myNewQueue.MonitorTransactionalDeadLetter();

            return;
        }
        
        // References public queues.
        public void SendPublic()
        {
            MessageQueue myQueue = new MessageQueue(".\\myQueue");
            myQueue.Send("Public queue by path name.");

            return;
        }

        // References private queues.
        public void SendPrivate()
        {
            MessageQueue myQueue = new 
                MessageQueue(".\\Private$\\myQueue");
            myQueue.Send("Private queue by path name.");

            return;
        }

        // References queues by label.
        public void SendByLabel()
        {
            MessageQueue myQueue = new MessageQueue("Label:TheLabel");
            myQueue.Send("Queue by label.");

            return;
        }

        // References queues by format name.
        public void SendByFormatName()
        {
            MessageQueue myQueue = new 
                MessageQueue("FormatName:Public=5A5F7535-AE9A-41d4" + 
                "-935C-845C2AFF7112");
            myQueue.Send("Queue by format name.");

            return;
        }

        // References computer journal queues.
        public void MonitorComputerJournal()
        {
            MessageQueue computerJournal = new 
                MessageQueue(".\\Journal$");
            while(true)
            {
                Message journalMessage = computerJournal.Receive();
                // Process the journal message.
            }
        }

        // References queue journal queues.
        public void MonitorQueueJournal()
        {
            MessageQueue queueJournal = new 
                MessageQueue(".\\myQueue\\Journal$");
            while(true)
            {
                Message journalMessage = queueJournal.Receive();
                // Process the journal message.
            }
        }
        
        // References dead-letter queues.
        public void MonitorDeadLetter()
        {
            MessageQueue deadLetter = new 
                MessageQueue(".\\DeadLetter$");
            while(true)
            {
                Message deadMessage = deadLetter.Receive();
                // Process the dead-letter message.
            }
        }

        // References transactional dead-letter queues.
        public void MonitorTransactionalDeadLetter()
        {
            MessageQueue TxDeadLetter = new 
                MessageQueue(".\\XactDeadLetter$");
            while(true)
            {
                Message txDeadLetter = TxDeadLetter.Receive();
                // Process the transactional dead-letter message.
            }
        }
    }
}