download a text separately a text found within a textbox

Question

Picking a given text within another textbox or richtextbox does not matter when there is an incidence of detailed text, e.g.: "text": take out of double quotes when the next sentence is found and take to a separate textbox field

I wrote this code can select the text I’m looking for inside a textbox.

I put an image below to explain better what I need

 Private Sub Button5_Click(sender As Object, e As EventArgs) Handles Button5.Click

        Dim i As Integer = 0
        Dim strTexto As String
        strTexto = TextBox3.Text

        RichTextBox1.Text = RichTextBox1.Text


        While i < RichTextBox1.Text.LastIndexOf(strTexto)
            RichTextBox1.Find(strTexto, i, RichTextBox1.TextLength, RichTextBoxFinds.None)
            RichTextBox1.SelectionBackColor = Color.Orange
            i = RichTextBox1.Text.IndexOf(strTexto, i) + 1

            txt_resultado.Text = i.ToString
        End While

    End Sub