C#，怎么进行封装，没学明白

建立一个C#定义宝马品牌（BMW）类，应当：
BMW有几个私有属性：型号(type)名称（Name），价格（price）
对属性进行封装
然后为构造函数进行重载，提供为1、2、3个属性赋值，一个都不赋值
定义方法show()，该方法负责输出宝马所有基本信息；
在Main中测试，要求每个构造函数的情况都要测试到

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


public  class BMWClass {

    private string type;
    /// <summary>
    /// 封装type
    /// </summary>
    public string Type { get { return type; } set { type = value; } }

    private string name;
    /// <summary>
    /// 封装name
    /// </summary>
    public string Name { get { return name; } set { name = value; } }


    private string price;
    /// <summary>
    /// 封装price
    /// </summary>
    public string Price { get { return price; } set { price = value; } }

    /// <summary>
    /// 一个都不赋值
    /// </summary>
    public BMWClass() { }
    /// <summary>
    /// 赋值一个
    /// </summary>
    /// <param name="_type"></param>
    public BMWClass(string _type) {
        type = _type;
    }
    /// <summary>
    /// 赋值两个
    /// </summary>
    /// <param name="_type"></param>
    /// <param name="_name"></param>
    public BMWClass(string _type, string _name) {
        type = _type;
        name = _name;
    }
    /// <summary>
    /// 赋值三个
    /// </summary>
    /// <param name="_type"></param>
    /// <param name="_name"></param>
    /// <param name="_price"></param>
    public BMWClass(string _type, string _name, string _price) {
        type = _type;
        name = _name;
        price = _price;
    }
    /// <summary>
    /// 输出所有信息
    /// </summary>
    public void show() {
        Console.WriteLine("type = " + type + " name = " + name + " price =" + price);
    }
}

static void Main(string[] args)
        {
            BMWClass bMW = new BMWClass();
            bMW.Type = "1";
            bMW.Name = "X1";
            bMW.Price = "10万";
            bMW.show();

            BMWClass bMW1 = new BMWClass("2");
            bMW1.Name = "X2";
            bMW1.Price = "20万";
            bMW1.show();

            BMWClass bMW2 = new BMWClass("3", "X3");
            bMW2.Price = "30万";
            bMW2.show();

            BMWClass bMW3 = new BMWClass("4", "X4","40万");
            bMW3.show();
        }

如果我没理解错的话 应该是这个意思

做了一点升级：

    internal class Program
    {
        static void Main(string[] args)
        {
            BMW_Model model1 = new BMW_Model();

            BMW_Model mode2 = new BMW_Model("名称");

            BMW_Model model3 = new BMW_Model("名称", "方式", 28000);

            BMW_Model model4 = new BMW_Model(type: "方式");
        }
    }

    public class BMW_Model
    {
        #region 方式一
        public string Name { get; set; }
        #endregion

        #region 方式二
        private string _type;

        //public string Type { get { return _type; } }  // 只读
        public string Type { get { return _type; } set { _type = value; } }     // 可读可写
        #endregion

        #region 方式三
        private decimal _price;
        //public decimal Price { get => _price; }
        public decimal Price { get => _price; set => _price = value; }
        #endregion

        public BMW_Model(string name = null, string type = null, decimal? price = null)
        {
            this.Name = name ?? string.Empty;
            this._type = type ?? string.Empty;
            this._price = price ?? 0;
        }
    }