Android Question How can i make my app Update itself... with a click

Sub JobDone (Job As HttpJob)
  If Job.Success = True Then
      Select Job.JobName
....
        Case "Job2"
            Dim out As OutputStream
            out = File.OpenOutput(File.DirRootExternal,"rt-z.apk",False) 'Don't see that works..
            File.Copy2(Job.GetInputStream,out) 'Don't see that works..
            out.close
            'run apk to install
            Dim iIntent As Intent
            iIntent.Initialize(iIntent.ACTION_VIEW, file:///sdcard/rt-z.apk) 'can't find anyhting because nothing downloaded ?????
            iIntent.SetType("application/vnd.android.package-archive")
            StartActivity(iIntent)
      End Select
  Else
      ToastMessageShow(Job.ErrorMessage, True)
.....
  End If
  Job.Release
End Sub
 
 
Sub Button4_Click
job2.Initialize("Job2", Me)
job2.Download("the domain and the file exactly with http at start") ' can't understand if that works..
End Sub

Sub ActualitzacionAPP
  
    If File.Exists(File.DirDefaultExternal,"result.apk") Then
        File.Delete(File.DirDefaultExternal,"result.apk")
    End If
  
    HttpUtils.CallbackActivity = "Sincronizar"
    HttpUtils.CallbackJobDoneSub = "JobDone"
    HttpUtils.CallbackUrlDoneSub = "UrlDone"
    HttpUtils.CallbackProgressSub="ProgressHTTP"
    url="http://www.mydomain.com/result.apk"
    HttpUtils.Download("downloadFile",url)
  
End Sub


Sub JobDone (Job As String)
    Select Job
        Case "downloadFile"
        If HttpUtils.IsSuccess(url) Then
            HttpUtils.SaveFile(url,File.DirDefaultExternal,"result.apk")
            If File.Exists(File.DirDefaultExternal,"result.apk") Then
                Dim Intent1 As Intent
                Intent1.Initialize(Intent1.ACTION_VIEW, "file://" & File.Combine(File.DirDefaultExternal,"result.apk"))
                Intent1.SetType("application/vnd.android.package-archive")
                StartActivity(Intent1)
            End If
        End If
     End Select
End Sub