in your project edit Global.asax file and add the code below.
protected void Application_Start(object sender, EventArgs e)
{
RegisterRoutes(System.Web.Routing.RouteTable.Routes);
}
public static void RegisterRoutes(System.Web.Routing.RouteCollection routes)
{
routes.MapPageRoute("somename",
"folder/{text-id}",
"~/index.aspx");
}
then in your index.aspx you can find this variable as
string text_id = RouteData.Values["text-id"].ToString();
further ref http://code.msdn.microsoft.com/Easy-Steps-to-URL-2f792901