You have several options when it comes to doing authentication in MVC:
The built in Forms Authentication can allow you to limit access to different areas of your application based on Role, User among other things and it is quite easy to implement using the [Authorize] attribute.
The following would require the user be logged in:
[Authorize]
public ActionResult YourActionNameGoesHere()
{
}
Likewise, the following would require the user be logged in AND be an Administrator:
[Authorize(Roles="Administrator")]
public ActionResult YourActionNameGoesHere()
{
}
Those were just a few methods of accomplishing it, as you can see there are MANY different methods of accomplishing this - I hope this might have shed a bit of light in helping you decide.