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

        If ValidaTextBox() = False Then
            MessageBox.Show("Compilare i campi correttamente")
        Else
            MessageBox.Show("Compilare i campi correttamente")
        End If


    End Sub

    Function ValidaTextBox() As Boolean

        ValidaTextBox = True
        If TextBox1.Text = "" Then
            TextBox1.BackColor = Color.Red
            ValidaTextBox = False
        End If

        If TextBox1.Text = "" Then
            TextBox2.BackColor = Color.Red
            ValidaTextBox = False
        End If

    End Function