Public Class Form1
    Private getSize = Me.FileSize(TextBox1.Text)
    Private Function GetFileSize(ByVal MyFilePath As String)
        Dim fileDetail As IO.FileInfo
        fileDetail = My.Computer.FileSystem.GetFileInfo(MyFilePath)
        Return fileDetail.Length
    End Function
    Sub DoDownload()
        DownloadFile(TextBox1.Text, TextBox2.Text)
    End Sub
    Sub DownloadFile(ByVal uri As String, ByVal destFile As String, _
Optional ByVal username As String = Nothing, Optional ByVal pwd As String = _
Nothing)
        Dim wc As New System.Net.WebClient
        If Not username Is Nothing AndAlso Not pwd Is Nothing Then
            wc.Credentials = New System.Net.NetworkCredential(username, pwd)
        End If
        wc.DownloadFile(uri, destFile)
    End Sub
    Function FileSize(ByVal url As String)
        Dim Request As System.Net.WebRequest
        Dim Response As System.Net.WebResponse
        Dim SizeFile As Integer

        Request = Net.WebRequest.Create(url)
        Request.Method = Net.WebRequestMethods.Http.Head

        Response = Request.GetResponse
        SizeFile = Response.ContentLength
        Return SizeFile
    End Function
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Timer1.Interval = 100
        If Timer1.Enabled = False Then
            Timer1.Enabled = True
        Else
            Timer1.Enabled = False
        End If
        Dim t As New System.Threading.Thread(AddressOf Me.DoDownload)
        t.Start()
    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        Dim value1 As Integer
        Dim value2 As Integer
        Dim value3 As Integer
        value1 = getSize
        value2 = GetFileSize(TextBox2.Text)
        value3 = value2 / value1 * 100
        ProgressBar1.Value = value3
    End Sub
End Class