Generic Class doubt how to pass object and get the desired result

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{

    public class Customer
    {

        public int CusomerId { get; set; }
        public string CustomerName { get; set; }
        public int CustomerAge { get; set; }
    }

    public class Test<T>
    {

        T _value;

        public Test(T t)
        {

            _value = t;
        }

//i am trying here to get the customer object from _value which i assigned in _value
//i cant even use foreach in generic class...
        public void write()
        {
       

        }

    }

    class Program
    {
        static void Main(string[] args)
        {
            Customer obj = new Customer();
            obj.CusomerId = 1001;
            obj.CustomerAge = 23;
            obj.CustomerName = "Anurag";

            Test<object> T1 = new Test<object>(obj);
            T1.write();
            Console.ReadLine();
        }
    }
}