Beginner Need Help!!!!

See more:

C#

I am doing a simple search on Richtext box, using web form application
I created a "Search" button, TextBox and a RichtextBox
I need to eliminate these word from user typing in the search box
The words are

(the, and, of, to, that, in, he, shall, for, unto, i, his, a, they, be, is, not, him, them, it, with, all, thou, was, thy, which, my, me)

The Code is:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace search_bar_w_richtextbox
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            int index = 0;
            while (index < richTextBox1.Text.LastIndexOf(textBox1.Text))
            {
                richTextBox1.Find(textBox1.Text, index, richTextBox1.TextLength, RichTextBoxFinds.None);
                richTextBox1.SelectionBackColor = Color.Green;
                index = richTextBox1.Text.IndexOf(textBox1.Text, index) + 1;
            }
        }
    }
}

If any one know how to eliminate those word from user typing,
Can you post the full Code !!!!