I think they're asking you, did you use Photoshop and use layers.
Ah. Nope, it was all created with the paint tool on DAmuro, which in hind sight wasn't such a great idea as it took an ungodly amount of time to finish.
If I knew how to use Photoshop, which I don't, this painting would come out much better. Definitely! But I'm happy with how this Concept art turned out.