How to scan directories and subdirectories with treeview?

This is what i have so far please please help me in getting this to scan directories



Imports System.IO
Public Class form1

Private Shared Sub FillOneLevel(ByVal root As TreeNode, ByVal path As String)
Dim di As New DirectoryInfo(path)
Try
For Each subFolder As DirectoryInfo In di.GetDirectories()
Dim node As New TreeNode(subFolder.Name) With {.Tag = subFolder.FullName}
root.Nodes.Add(node)
Next subFolder
Catch ex As Exception
' do something
End Try
End Sub

Private Sub form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim drives() As String = Environment.GetLogicalDrives()
For Each dr As String In drives
Dim node As New TreeNode(dr) With {.Tag = dr}
FillOneLevel(node, dr)
tv1.Nodes.Add(node)
Next dr
tv1.Nodes(0).Expand()
End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
LookAtDir(lblMessage.Text)
End Sub

Private Sub LookAtDir(ByVal path As String)
Try
For Each dir As String In Directory.GetDirectories(path)
LookAtDir(dir)
Next
'...Do something with the directory.
Catch ex As UnauthorizedAccessException
End Try
End Sub

Private Sub tv1_AfterSelect(ByVal sender As System.Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles tv1.AfterSelect
lblMessage.Text = tv1.SelectedNode.Tag
End Sub
End Class