How to find ID from images stored in labels?

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C#

I have this Code. It works the Images and the mouse over titel are showing. Now I wont to place a TextBox to write Information. The data should be saved in the database. My Problem is: I dont know how to find the correct ID; so the Information will be saved in the correct database line.

What I have tried:

protected void Save_Click(object sender, EventArgs e)
   {

       string constr = ConfigurationManager.ConnectionStrings["conn"].ConnectionString;
       using (SqlConnection conn = new SqlConnection(constr))
       {
           conn.Open();
           string query = @"UPDATE Pic SET desc=@desc where ID=@ID";
           using (SqlCommand cmds = new SqlCommand(query, conn))
           {
               cmds.Parameters.AddWithValue("@desc", txtdesc.Text);
               cmds.Parameters.AddWithValue("@ID", WHAT COMES HERE?);

               cmds.ExecuteNonQuery();
           }
       }

   }

<pre>protected void TreeView1_SelectedNodeChanged(object sender, EventArgs e)
    {
        string a = "";
        string g = "";


        string x = TreeView1.SelectedNode.ValuePath.Replace("GO/", "");

        string sql = @"Select * From Pic  ORDER BY Place";
       

       
        SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["conn"].ConnectionString);
        con.Open();
        SqlCommand cmd = new SqlCommand(sql, con);
        SqlDataReader r = cmd.ExecuteReader();
        int lb = 0;
        while (r.Read())
        {
               a += "<li><img src=\"/ImageHandler.ashx?id=" + r["ID"].ToString() + "\" alt=\"" + r["Text"].ToString() + "\"/></li>";
            g += "<a href=\"#\" title=" + r["title"].ToString() + "><img src=\"/ImageHandler.ashx?id=" + r["ID"].ToString() + "&width=35&height=16\" alt=\"\" /></a>";
            lb++;
        }
        con.Close();
        phBilder.Text = a;
        phTumbs.Text = g;
}