Interface in c#

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System;

namespace InterfaceApplication

{

    public interface ITransactions

    {

      

        void showTransaction();

        double getAmount();

    }

    public class Transaction : ITransactions

    {

        private string tCode;

        private string date;

        private double amount;

        public Transaction()

        {

            tCode = " ";

            date = " ";

            amount = 0.0;

        }

        public Transaction(string c, string d, double a)

        {

            tCode = c;

            date = d;

            amount = a;

        }

        public double getAmount()

        {

            return amount;

        }

        public void showTransaction()

        {

            Console.WriteLine("Transaction: {0}", tCode);

            Console.WriteLine("Date: {0}", date);

            Console.WriteLine("Amount: {0}", getAmount());

        }

    }

    class Tester

    {

        static void Main(string[] args)

        {

            Transaction t1 = new Transaction("001", "8/10/2012", 78900.00);

            Transaction t2 = new Transaction("002", "9/10/2012", 451900.00);

            t1.showTransaction();

            t2.showTransaction();

            Console.ReadKey();

        }

    }

}