nopCommerce 2.40 how to display img src url from controller

In BaseNOPController.cs

        public string MyChart1YearString(this HtmlHelper helper)
        {
            string url = "http://filecache.xignite.com/xGetFile.aspx?key=w7gTwyUIxz6oiFxF2A6vr6OAHe1F99Kk9PY4PeEmAUHTIruDs12shGKoiAEuZaKhlCxCopEjJyCimFAv6jWMhOWzxbPgDjoH";
            return url;
        }

and I have <img src="@Url.Action("MyChart1YearString")" alt="" /> in _ColumnsThree.cshtml (not working)


How do I get the source for the image.