Ground school is like every other ground school and since you already fly the plane it should be even easier.

I would study the caution/warning panel and what makes each light go on because the oral will most likely be mainly focused on that. They'll probably ask you limitations from whatever model you fly also.

Study LGA/JFK approach plates because that's where you'll be flying the whole time.

Other than that just know the profiles and remember that it's a sim so it won't fly like the real plane. If you have any other specific questions let me know.