c#Console_ClassmethodError

using System;

namespace test //c# in console
{
    class TestClass
    {
        //members
        private int mCod;

        //properties
        public int Cod
        {
            get{
                return mCod;
            }
            set{
                mCod = value;
            }
        }
        //methods
        public void greetings()
        {
            Console.WriteLine("Hello!");
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            TestClass testC = new TestClass();

            void functest() //U can't declare with privacy and outside Main
            {
                Console.WriteLine("main func test");
            }
            bool i = true;

            if(i)
                Console.WriteLine("Hello World");
            functest();

            //using methods and properties of an internal class
            testC.Cod = 3;
            Console.WriteLine(testC.Cod + "\n");
            testC.greetings;

        }
    }
}