[oneyemenweb2]

كود :

Dim len As Integer = Me.richTextBox1.TextLength
Dim index As Integer = 0
Dim lastIndex As Integer = Me.richTextBox1.Text.LastIndexOf(Me.textBox1.Text)

While index < lastIndex
    Me.richTextBox1.Find(Me.textBox1.Text, index, len, RichTextBoxFinds.None)
    Me.richTextBox1.SelectionBackColor = Color.Yellow
    index = Me.richTextBox1.Text.IndexOf(Me.textBox1.Text, index) + 1
End While