Be sure to place the water scape layer UNDER the layer with the girl. This is important, we placed the girl first in order to be able to see what proportion are we creating with the landscape, however, remember, that she shall always be the top later.
Using the Eraser tool, with soft edge, 40 or 50 px size, draw a line (horizon), which will he around the level of the main figure’s eyes. This is ideally, but if you use a taller person, or not a sitting figure, of course you can draw the horizon wherever you wish.
In order to make sure that your line is straight, press the Shift button while pressing the mouth, this way, even if your hand will hove, the line will remain straight.
Now we need sky. Don’t look for any spy picture, because we mostly need a horizon line (with mountains, or just a stroke of land) rather than mere clouds.
The hue of the picture is not important, all you need is a cloudy interface with a bit of land to symbolize the horizon.
Paste your clouds photo unto the fantasy canvas, UNDER the water scape layer.
The horizon line of the water has to be a little darker, so u can go back to the background later (blue canvas) and brush it with black or a darker blue hue.
Create a new layer.
Select a Round Brush with a sharp edge (do not use a soft edge here!) and Make a stamp near the figure, as shown on the picture below.