Asp - Send a popup message

 To send a message follow the next steps:

1. Add the reference:  using AjaxControlToolkit; 
2. Build the message through an alert using JQuery
3. Use the method RegisterClientScriptBlock 

 The function should look like this:

        StringBuilder sb = new StringBuilder();
        sb.Append("<script type=\"text/javascript\">alert('");
        sb.Append(mensaje.Replace("'", ""));
        sb.Append("'); ");
        sb.Append("window.location.href='");
        sb.Append(url);
        sb.Append("';</script>");
       ToolkitScriptManager.RegisterClientScriptBlock(this, typeof(Button), "Mensaje", sb.ToString(), false);