Sorry for the confusion. I guess I'm misunderstanding his entire article concerning rivers. You've obviously mastered it. Mind if I e-mail you and chat about it?
Hey there. Sorry, I've only just read your message.
Umm, I'm not sure I fully understand your problem. If I'm correct in where you are in the tutorial, then all you need to do is to INVERT the layer so that white becomes black and vice versa.
I've been doing Jeremy Elford's tutorial taking your advice and am stuck on rivers. Maybe we could chat and figure it out? I'm unsure how he goes from black rivers to white ones.
Hope to hear!