Random Mac address changer with C#

Question

I'm a newbie developer! I study C# now, i want to change Mac address only use C# (with registry) (not bat OR cmd) how can I do? This code is Make Random 12 random string with english and number and i want to change mac address to the random string.. Thanks!

using System;
using System.Timers;
using System;
using System.Net;
using System.IO;
using System.Diagnostics;
using System.Linq;
using Microsoft.Win32;
namespace auto_mac_address_changer
{
    class MainClass
    {

        public static string GetRandomPassword(int _totLen)
        {
            Random rand = new Random(); string input = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; var chars = Enumerable.Range(0, _totLen).Select(x => input[rand.Next(0, input.Length)]); return new string(chars.ToArray());
        }

        public static void Main(string[] args)
        {


                bool networkUp = System.Net.NetworkInformation.NetworkInterface.GetIsNetworkAvailable();


            reg = reg.OpenSubKey("Software\\Your Program Name", true);


            while (true)
            {
                if (networkUp == false)
                {
                    string a = GetRandomPassword(12);
                    //here need to be change registry relative Mac Address

                }


            }

        }
    }
}