OK, never mind, I figured out what I was doing wrong with my dirt, and fixed it.

Now I'm on Post 11, working on mountains. I've got my mountain layer, I've added my MountainNoise layer, but I'm thick as a brick when I am creating my MountainClip layer. I'm referring back to Post 4 for the TLS strategem, but I'm really lost on what to do.

Can someone explain the Mountain Clip layer to me, like I'm five years old?