how to show uploaded picture through session

protected void Button2_Click1(object sender, EventArgs e)
       {
           StartUpLoad();
       }
       private void StartUpLoad()
       {
           //get the file name of the posted image
              string username = (string)(Session["UserAuthentication"]);

              string imgName = username;
           //sets the image path
           string imgPath = "Images/gallery/adil/" + imgName;

           //get the size in bytes that

           int imgSize = FileUpload1.PostedFile.ContentLength;

           //validates the posted file before saving
           if (FileUpload1.PostedFile != null && FileUpload1.PostedFile.FileName != "")
           {
               // 10240 KB means 10MB, You can change the value based on your requirement
               if (FileUpload1.PostedFile.ContentLength > 1024000)
               {
                   Page.ClientScript.RegisterClientScriptBlock(typeof(Page), "Alert", "alert('File is too big.')", true);

               }
               else
               {
                   //then save it to the Folder
                   FileUpload1.SaveAs(Server.MapPath(imgPath));
                   Image1.ImageUrl = username + imgPath;
                   Page.ClientScript.RegisterClientScriptBlock(typeof(Page), "Alert", "alert('Image saved!')", true);

               }

           }


       }

<asp:Image
              ID="Image1" runat="server"
           ImageUrl="~/images/gallery/adil/dafult.jpg" Height="379px" Width="614px" />