Text Search And Replacement - vb.net

Question

I am working with visual basic and i'm creating a function which performs a search for each word that is entered into a richtextbox. As a word is being entered into RichTextBox2 a search Is performed in RichTextBox1 and the text is highlighted .
RichTextBox1 and RiochTextBox2 are read only , RichTextBox2 is able to be written in via code while RichTextBox1 has only default text (A directory of words). There is also RichTextBox3 which holds a copy of RichTextBox2's text
RichTextBox3.Text = RichTextBox2.Text
this is the code for the function .
public class textsearch
Private intPosition As Integer
Private Sub NextButton_Click(sender As Object, e As EventArgs) Handles NextButton.Click
generatekanji()
' Static intStart As Integer
'used to select compare method
Dim intStart As Integer
Dim objType As Object
Dim lastWord As String = RichTextBox2.Text.Split(" ").Last
objType = CompareMethod.Text
'set starting position to 1
intPosition = 1
'use the InStr function to look up a staring position of a search string in a given text box using objType (case-insensitive or case-sensitive)
intStart = InStr(intPosition, RichTextBox1.Text, lastWord, objType) ' what it searches
If intStart > 0 Then
'set starting select position on a textbox and select the search string
RichTextBox1.SelectionStart = intStart - 1
RichTextBox1.SelectionLength = lastWord.Length 'highlights the searched word
RichTextBox1.Select()
End If
End Sub
End Class
This is a very useful function but the main issues are
(1) because RichTextBox1 is read only , you gear the "ding" sound each time a search is being performed and it gets very annoying.
(2) I am unable to find a way to select the character whenever a word is found , or how to replace the word in RichTextBox3 with the character next to the searched word.
Could someone help with this problem .

Answer 1

When I use this code the search word is highlighted with no dinging, in a readonly richtextbox:
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
Dim SearchWord As String = RichTextBox2.text
Dim SelStart As Integer = InStr(RichTextBox1.Text, SearchWord, CompareMethod.Text)
If SelStart > 0 Then
RichTextBox1.Select(SelStart - 1, SearchWord.Length)
RichTextBox1.Focus()
For Each line In RichTextBox1.Lines
If line.Contains(SearchWord) Then
RichTextBox3.Text = line.Split()(0)
End If
Next
End If
End Sub
I'm wondering if the dinging is coming from the generatekanji() routine.