using System;

public class Program

{

    public static void Main()

    {

        var newValue = 1;

        var myArray = new int[5] { 2, 3, 4, 5, 6 };

        var newArr = new int[myArray.Length + 1];

​

        myArray.CopyTo(newArr, 1);

        newArr[0] = newValue;

        //debug

        for(var i = 0; i < newArr.Length; i++){

            Console.WriteLine(newArr[i].ToString());

        }

    }

}