upload multiple images and display them

i wont to upload malty images from FileUpload store theme in cookies and display the images in an update penal in the same time i get only the last photo updated to the update anal

and this the code behind in C# :

protected void addphoto_Click(object sender, EventArgs e)
    {
        if (FileUpload1.HasFile )
        {
            for (int i = 0; i < FileUpload1.PostedFiles.Count; i++)
            {
                string vale = Guid.NewGuid().ToString() + ".png";
                string path = Server.MapPath("").Replace("user", "pimg") + "\\" + vale;
                FileUpload1.SaveAs(path);
                b = "~/pimg/" + vale;
                //string test = "~/pimg/d13526f4-9713-48fa-bb5d-a37f27b0366e.png";
                if (Request.Cookies["aa"] == null)
                {
                    Response.Cookies["aa"].Value = b;
                }
                else
                {
                    Response.Cookies["aa"].Value = Request.Cookies["aa"].Value + "|" + b;
                }
            }

        }

if (Request.Cookies["aa"] != null)
        {
            s = Convert.ToString(Request.Cookies["aa"].Value);
            string[] strarr = s.Split('|');
            foreach (var item in strarr)
            {
                //string html = "<a class='btn btn-primary' style='padding: 10px; margin: 10px' href='deletitem?myid=" + item.ProdectID + "'>" + item.Name + "</a>" + "";
                Image img = new Image();
                img.ImageUrl = item.ToString();
                img.Height = 150;
                img.Width = 100;
                UpdatePanel2.ContentTemplateContainer.Controls.Add(img);

            }

}
}