Tab event of textbox

 Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    TextBox1.TabIndex = 0
    TextBox2.TabIndex = 1
    TextBox3.TabIndex = 2
    TextBox1.Text = 1
  End Sub
  Private Sub TextBox2_Enter(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox2.Enter
    TextBox2.Text = 2
  End Sub
  Private Sub TextBox3_Enter(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox3.Enter
    TextBox3.Text = 3
  End Sub