ASP.NET - Validar si el usuario a iniciado sesion

@model MyModel.Models.MyController

@{

    ViewBag.Title = "Details";

}

<h2>Details</h2>

<p>

    @Html.ActionLink("Agregar", "Create", "MyController")

</p>

<div>

    <h4>MyController</h4>

    <hr />

    <dl class="dl-horizontal">

        <dt>

            @Html.DisplayNameFor(model => model.Titulo)

        </dt>

        <dd>

            @Html.DisplayFor(model => model.Titulo)

        </dd>

    </dl>

</div>

[Authorize]

    public class AccountController : Controller

{