Who is the actor in a Use Case Diagram?

An actor is a person, organization or system that interacts with your system. OpenID is none of these. Google is.

So you should model Google as the actor.

Both are valid choices. If you want to express that Google acts as a company you can add it as an actor. If you want to express that the user interacts with a general "OpenID Service" you can put it there as well.

Or you can combine it and name the actor "Google OpenID Service" to make it more specific.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.