Code behind to populate country n state

Please let me know if this is correct way of coding.
Please chk the underlined code. And aslo if i use" If Not IsPostBack Then" code it will not work.
Let me know
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click     
  Dim _coun As String = Request.Form.Get("country")    
    Dim _state As String = Request.Form.Get("state")
        'If Not IsPostBack Then

        If photoUpload1.PostedFile IsNot Nothing AndAlso photoUpload2.PostedFile IsNot Nothing AndAlso photoUpload3.PostedFile IsNot Nothing Then

            Dim image1 As String = System.IO.Path.GetFileName(photoUpload1.PostedF ...