vb.net - vb.net ファイルの保存/読み込みとその他の問題

Question

連絡先とその連絡先に関する情報を保存するために使用できる簡単なプログラムを作成しています。保存/読み込み機能と挿入された連絡先の合計数に問題があります。ほとんどのコードは "TheNewBoston" のチュートリアルから取ったもので、気に入ったので、さらに機能を追加しようとしています。ソースコードは次のとおりです。

Public Class Form1

    Dim myCustomers As New ArrayList
    Dim FILE_NAME As String = "C:\test.txt"

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        AddCustomer("Sam", "Bond", "sambond@msn.com", "9541032163")
        AddCustomer("Merry", "Jackson", "merryjackson@msn.com", "8872101103")
        AddCustomer("Rachel", "Smith", "rachelsmith@msn.com", "4839078565")
        'DOESN'T WORK''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
        If System.IO.File.Exists(FILE_NAME) = True Then
            'AddCustomer.System.IO.StreamReader(FILE_NAME)
            'or
            AddCustomer(System.IO.StreamReader(FILE_NAME))
        Else
            MessageBox.Show("File does not exist.")
        End If
    End Sub

    'Public variables
    Private Structure Customer
        Public FirstName As String
        Public LastName As String
        Public Email As String
        Public Phone As Decimal

        'Does Name = First&Last Name
        Public ReadOnly Property Name() As String
            Get
                Return FirstName & " " & LastName
            End Get
        End Property

        'Shows the customers in the listbox properly overriding the default ToString function
        Public Overrides Function ToString() As String
            Return Name
        End Function

    End Structure

    'Declaring and connecting to type Customer
    Private objCustomer As Customer
    Private objNewCustomer As Customer

    'Makes customer format
    Private Sub AddCustomer(ByVal firstName As String, ByVal lastName As String, ByVal email As String, ByVal phone As Decimal)
        'declares objNewCustomer with the type of customer for use
        Dim objNewCustomer As Customer

        'Connects the Customer's 4 things to objNewCustomer
        objNewCustomer.FirstName = firstName
        objNewCustomer.LastName = lastName
        objNewCustomer.Email = email
        objNewCustomer.Phone = phone

        'Adds to myCustomers array list the objNewCustomer
        myCustomers.Add(objNewCustomer)
        'Adds customer Name to list
        listCustomers.Items.Add(objNewCustomer.ToString())
    End Sub

    'Avoids customer select error
    Private ReadOnly Property SelectedCustomer() As Customer
        Get
            If listCustomers.SelectedIndex <> -1 Then
                Return CType(myCustomers(listCustomers.SelectedIndex), Customer)
            End If
        End Get
    End Property

    'Enables select customer
    Private Sub listCustomers_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles listCustomers.SelectedIndexChanged
        DisplayCustomer(SelectedCustomer)
    End Sub


    'Loads the customers' information
    Private Sub DisplayCustomer(ByVal cust As Customer)
        txtName.Text = cust.Name
        txtFirstName.Text = cust.FirstName
        txtLastName.Text = cust.LastName
        txtEmail.Text = cust.Email
        txtPhone.Text = cust.Phone
    End Sub


    'Add User (pops up new window)
    Private Sub btnAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAdd.Click
        Form2.Show()
        'System.IO.File.WriteAllText("C:\test.txt", Textbox1.Text)
    End Sub

    'WORKS
    Private Sub btnTotal_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnTotal.Click
        txtTotal.Text = myCustomers.Count.ToString()
    End Sub

    'Private Total2 As Integer
    'experimenting
    'Private Sub DisTotal(ByVal Total As Integer)
    '    Do
    '        'total2 = myCustomers.Count.ToString()
    '        'txtTotal.Text = total2
    '        txtTotal.Text = Total
    '        System.Threading.Thread.Sleep(5000)
    '    Loop
    'End Sub

    Private Sub listTotal_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs)
        Total = myCustomers.Count
        'DOESN'T WORK''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
        Do
            'total2 = myCustomers.Count.ToString()
            'txtTotal.Text = total2
            txtTotal.Text = myCustomers.Count.ToString()
            System.Threading.Thread.Sleep(5000)
        Loop
    End Sub

    Private Total As Integer
    'DOESN'T WORK''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
    Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click
        Dim writer As New IO.StreamWriter(FILE_NAME)

        Try
            writer.Write("")
            writer.Close()
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        Finally
            writer.Close()
        End Try
    End Sub End Class

ヘルプ/ヒントをいただければ幸いです。また、修正されたコードブロックを投稿する場合は、それがどのように機能するか/何が間違っていたかを説明してください。