How to use BinarySearch Method on ArrayList

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;
namespace CollectionDirectories
{
    class sortArrayList
    {
        static int sr_no;
        static void Main()
        {
            
            ArrayList al = new ArrayList();
            al.Add("Hello");
            al.Add("World");
            al.Add("this");
            al.Add("is");
            al.Add("yes");
            al.Add("a");
            al.Add("test");
            al.Remove("test");
            al.Insert(4,"not");
// comment on output: In this list index of "World" is 1 but out put is different.
            Console.WriteLine("First Search ="+al.BinarySearch("World"))
Console.WriteLine("_______________");
            al.Sort();
            foreach (object s in al)
                Console.WriteLine(s.ToString());f
// comment on output: If reverseSort is used the output after reverse is length of arrarylist +1
            al.Sort(new reverseSort());
            Console.WriteLine("after reverse____________");
            foreach (object s in al)
            {
                sr_no++;
                Console.WriteLine(sr_no + ":" + s.ToString());
            }
            Console.WriteLine("sr. of word_______________");
          
            Console.WriteLine("Second Search = "+ al.BinarySearch("World"));
            Console.WriteLine("____________");
            foreach (object s in al)
                Console.WriteLine(s.ToString());
          
            Console.Read();
        }
        static int i;
        public class reverseSort : IComparer
        {
            int IComparer.Compare(Object x, Object y)
            {
                i++;
                Console.WriteLine(i+&" "+ x + " "+ y);
                  
                return ((new CaseInsensitiveComparer()).Compare(y, x));
            }
        }
    }
}