My first post here, and already a question

Almost all PS mapping tutorials start with Filter > Render > Clouds, then new layer, fill with 50% gray and hard mix. That gives you landmass and you continue to work on the mass of oceans and land.
(for example I found this one pretty good:

The question is - I drawn my own land onto paper with hand, scanned it, colored it with black only, used treshold to get the same result what the upper method do.
Here is a small part of big image just so you get what I did:

Name:  black-white-map.png
Views: 239
Size:  8.6 KB

Now the problem is, I got only 1 layer in my Photoshop (and it is filled with my image) - and it's called Background. All tutorials have clouds as their background, and all make ocean and the rest of the map by using first made clouds.

Can anyone help me how to skip that part with clouds, or should I create them anyway, then copy my image in when we come to landmass creation?

Thank you