How to open Rad Window on page load from Code Behind.

Rad Window on PageLoad:

using Telerik.Web.UI;

     RadWindow newWindow = new RadWindow();
     newWindow.NavigateUrl = "Test.aspx";
     newWindow.VisibleOnPageLoad = true;
     newWindow.Modal = true;
     newWindow.Width = 750;
     newWindow.Height = 480;
     RadWindowManager1.Windows.Add(newWindow);