ASP.NET MVC - Passing a parameter to my action method?

Question

    public ActionResult RenderMyThing(IList<String> strings)
    {
        return View("RenderMyView");
    }

How do I pass in strings?

        routes.MapRoute("MyRoute", "RenderMyThing.aspx", new { controller = "My", action = "RenderMyThing" });

Is there a way I could pass in strings here?

Secondly, how does ASP.NET MVC know that action is my action, and controller is my controller. Like I saw this in samples, and it does work, but isn't it just an anonymous object with no type?