So I have a couple of the layer card ex: [item=Layer Card: Head] and I'm not totally sure how/where to use them. Or really even what they do so I was hoping someone could explain them to me.

You use them to do alchemy! It only works if you have a zombie skin active, though. But you take them to the Alchove in the Shadowglen Underground and you can combine them with tokens and tinctures from the Philosopher's Store to make different items. The whole list of items is here.

If you ever need a zombie to do some alchemy for you, let me know! All you need to do is give me the items you want to combine and I will combine them for you :)

The same as Elsa has offered, I'd be happy to offer my zombie-self if you need help with any alchemy stuff.