Visual Basic

Public Class Form1
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim login As String = Me.TextBox1.Text.ToUpper
        Dim clave As String = TextBox2.Text
        If login = "VB" And clave.ToUpper = "NET" Then
            MessageBox.Show("Usuario Válido", "Mensaje", MessageBoxButtons.OK, MessageBoxIcon.Information)
        Else
            MessageBox.Show("Usuario no Válido", "Mensaje", MessageBoxButtons.OK, MessageBoxIcon.Information)
        End If
    End Sub
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        If MessageBox.Show("Desea Salir?", "Confirmar", MessageBoxButtons.YesNo, MessageBoxIcon.Question) = Windows.Forms.DialogResult.Yes Then
            REM Cierra el form
            Me.Close()
        End If
    End Sub
    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        MessageBox.Show("Ingrese su login y password", "Mensaje", MessageBoxButtons.OK, MessageBoxIcon.Information)
    End Sub
    Private Sub Form_1FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
        If MessageBox.Show("Desea Salir?", "Confirmar", MessageBoxButtons.YesNo, MessageBoxIcon.Question) = Windows.Forms.DialogResult.No Then
            e.Cancel = True
        End If
    End Sub