This is hard to explain. Shoes like the Ghost with a 12mm heel to toe drop are designed to heel strike. 90-95% of all runners are heel strikers. Heel striking isn't inherently bad. It's whether the runner is landing hard on the heel (overstriding) vs. landing lightly on the heel with the knee slightly bent, which is okay. As a novice, you are most likely a heel striker.
As a novice, one simple way to see if you're running correctly is to run in a pack and listen for your footstrike. If you can clearly hear your footstrike over the other runners, you're probably overstriding. Overstriding puts you at higher risk for shin splints and knee problems.
Personally, I'm a forefoot striker. I would have a hard time running in a 12mm drop shoe. I'm more comfortable in a 6mm drop shoe.
Since you're just starting out, don't worry about heel vs forefoot. Just run. If your coach is knowledgeable about running form, ask for advice about your form.
What you want to watch out for is pain on one side and not on the other. Some pain as you get used to running is normal. But if your left knee hurts and your right doesn't, you need to ask someone about it.
Some guys here will tell you, "You're overthinking this. Just run." That's actually not bad advice. Best of luck!!!