Distant Trees

I’m struggling with painting distant trees. In the tutorial Field of Gold – my far trees are a hot mess. I’ve made several attempts and am creating different “messes”. In the Field of Gold – am I seeing it correctly that you put clean water in the sky and then cobalt blue – then you put clean water and paint the the distant field. Is the paper where the violet then goes dry and then your liquid paint moves to the wet area? Also with the green trees – is that part of the paper dry?

Thanks!