data student application. need help with some codes to display student info..Visual basic

Public Class Form1
    Dim sr As IO.StreamReader
    Dim sw As IO.StreamWriter
    Dim line As String
    Structure Student
        Dim first As String
        Dim last As String
        Dim major As String
        Dim phone As String
        Dim email As String
        Dim gpa As Double
    End Structure

    Private Sub btnExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExit.Click
        Me.Close()
    End Sub
    Private Sub btnStart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStart.Click
        Dim array() As String
        sr = IO.File.OpenText("H:\Students\Debug\Students.txt")
        line = sr.ReadLine()
        array = line.Split(" ")
        txtFirst.Text = array(0)
        txtLast.Text = array(1)
        txtMajor.Text = array(2)
        txtPhone.Text = array(3)
        txtEmail.Text = array(4)
        txtGpa.Text = array(5)
        If sr.Peek = -1 Then
            sr.Close()
            lstStudents.Items.Add(array(0))
        End If
    End Sub
    Private Sub btnNext_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnNext.Click
        Dim i As Integer
        Dim array() As String
        sr = IO.File.OpenText("H:\Students\Debug\Students.txt")
        For i = 0 To 20
            line = sr.ReadLine()
            array = line.Split(" ")
            txtFirst.Text = array(0)
            txtLast.Text = array(1)
            txtMajor.Text = array(2)
            txtPhone.Text = array(3)
            txtEmail.Text = array(4)
            txtGpa.Text = array(5)
            If sr.Peek <> -1 Then
                line = sr.ReadLine()
            End If
        Next
        If sr.Peek = -1 Then
            sr.Close()
            lstStudents.Items.Add(array(0))
        End If
    End Sub
    Private Sub btnSort_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSort.Click
        Dim n As Integer = 0
        sr = IO.File.OpenText("H:\Students\Debug\Students.txt")
        Do While (sr.Peek <> -1)
            line = sr.ReadLine
            n += 1
        Loop
        sr.Close()
        Dim stud(n - 1) As Student
        Dim index As Integer
        Dim a() As String
        Dim record As String
        sr = IO.File.OpenText("H:\Students\Debug\Students.txt")
        For index = 0 To n - 1
            record = sr.ReadLine
            a = record.Split(" ")
            stud(index).first = a(0)
            stud(index).last = a(1)
            stud(index).major = a(2)
            stud(index).phone = a(3)
            stud(index).email = a(4)
            stud(index).gpa = a(5)
        Next
        sr.Close()
        Dim temp As Student
        Dim num As Integer
        For i = 0 To n - 2
            For index = i + 1 To n - 1
                If stud(index).last < stud(index - 1).last Then
                    temp = stud(index)
                    stud(index) = stud(n - 1)
                    stud(n - 1) = temp
                End If
            Next
        Next
       
        sw = IO.File.CreateText("H:\Students\Debug\Students.txt")
        For index = 0 To num - 1
            line = stud(index).first & " " & stud(index).last & " " & stud(index).major & " " & stud(index).phone & " " & stud(index).email & " " & stud(index).gpa
            sw.WriteLine(line)
        Next
        sw.Close()
        lstStudents.Items.Clear()
        sr = IO.File.OpenText("H:\Students\Debug\Students.txt")
        For index = 0 To n - 1
            record = sr.ReadLine()
            lstStudents.Items.Add(record)
        Next
        sr.Close()

    End Sub
   
    Private Sub btnAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAdd.Click
       
        Dim first As String
        Dim last As String
        Dim major As String
        Dim phone As String
        Dim email As String
        Dim gpa As Double

        first = txtFirst.Text
        last = txtLast.Text
        major = txtMajor.Text
        phone = txtPhone.Text
        email = txtEmail.Text
        gpa = txtGpa.Text
        line = first & " " & last & " " & major & " " & phone & " " & email & " " & gpa
        sw = IO.File.AppendText("H:\Students\Debug\Students.txt")
        sw.WriteLine(line)
        sw.Close()


    End Sub
End Class