Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Main.Hide()
Prenos.Show()

End Sub

Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
Main.Hide()
Sistem.Show()
End Sub

I have those forms sistem,prenos a their design but project show me two errors:

Where is problem

Main.Hide()-Expression does not produce a value.

Prenos.Show() -Reference to a non-shared member requires an object reference.
How to resolve that ,is there problem with reference ,which to use?