I was going over the same tutorial and at the bottom it has this:
"That’s it. We now have a way to track time. As an added bonus, in the next article, we will use this timer to compute our frame rate. You will notice that the solution now will no longer build. This is because the classes in the file we added require DirectX to be referenced. We are going to cover which parts of DirectX we need in the next article."
I asume that is the problem, I have yet to do the next tutorial yet (going to do it right now).