How can I paint my landscape?

Thanks fot the answer, but I didn’t mean that.
I already have my basic texture for the ground. Now I wanted to paint my mountains, like this one here: http://youtu.be/tsXVP0fykBM?t=7m33s
But I have no option in “Target Layers” execpt "Painting Restriction.
it looks at the moment like this: http://puu.sh/bdfOH/d8cc0f2cc0.jpg