How do I make my button save results? - vb.net

Question

I've been playing around learning the ropes of VB.NET. I have started making my own small generator which just generates txt on the left hand side listbox based on whatever the user chooses in the combo box as you can see in the picture. I would like to configure the already Save Results to open a file dialog box and allow the user to say what is already in the listbox in a txt file in any directory he or she choose. Please look at my VB Program picture below to get a better understanding
My VB program
Imports System.IO
Public Class Form1
Private Sub Button11_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
ProgressBar1.Value = ProgressBar1.Value + 60 'change this to incrase green bar'
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
' declare the required variables
Dim i As Integer = 0
Dim item As String
Dim fileReader As StreamReader
' set the value min and max values of progress bar
' clear the contents of the ListBox1
ListBox1.Items.Clear()
' check whether an item is selected in the combox1
If ComboBox1.SelectedIndex <> -1 Then
' is selected get the item
item = ComboBox1.SelectedItem.ToString()
Else
' otherwise set item to empty
item = ""
End If
' depending on the item initialize the fileReader with
' with respective file name
If item.Equals("Random") Then
fileReader = New StreamReader("world mix.txt")
ElseIf item.Equals("China") Then
fileReader = New StreamReader("china.txt")
ElseIf item.Equals("Korea") Then
fileReader = New StreamReader("korea.txt")
ElseIf item.Equals("United Arab Emirates") Then
fileReader = New StreamReader("ae.txt")
ElseIf item.Equals("Russia") Then
fileReader = New StreamReader("ru.txt")
ElseIf item.Equals("USA") Then
fileReader = New StreamReader("usa lead.txt")
ElseIf item.Equals("New Zeland") Then
fileReader = New StreamReader("nz.txt")
Else
fileReader = New StreamReader("names.txt")
End If
' loop till end of the file
Do While fileReader.Peek() <> -1
' check whether the progress is less than 200
' if so just increment the progress bar value
If ProgressBar1.Value <= 100 Then
' set the line that is read into the listBox
ListBox1.Items.Add(fileReader.ReadLine().ToString())
' increment the iterator
End If
Loop
' close the file
fileReader.Close()
End Sub
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
' when stop button is clicked, just display a pop up message
MessageBox.Show("The progress bar has stopped!")
End Sub
Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
''This is the save results button button''
End Sub
End Class