This code can make your form transparent in 12 states with a trackbar.
Instead of Chat_Activated you can set Form1.

Private Sub Chat_Activated(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Activated
        TrackBar1.SetRange(1, 12)
        TrackBar1.Value = 12
    End Sub

    Private Sub TrackBar1_Scroll(ByVal sender As System.Object, ByVal e As System.EventArgs)
        Me.Opacity = TrackBar1.Value / 12
    End Sub