The first thing we will do is create several sketches in which we will shape the ideas we have for the fund we want to illustrate.
For this we will draw in blocks, without details, the basic shapes of our background.
We will draw what is farthest with light colors and what is closer to us with darker colors.
After we have several quick sketches done what we will do is select the one that we like the most and work from that.
We select the sketch with the selection tool, press Ctrl + T and stretch it to the size of our canvas.
Then, we lower the opacity of the layer and create a new layer on top, then we draw our sketch with a little more detail on that layer.
We color in different layers with gray tones each element according to the distance. The closer we are to the darkest and the further away from us the elements are, the clearer we paint them.
In the Layer - New Correction layer menu, we select Gradient Map.
Double click on the gradient that we like and press OK.
We see that all our drawing changed color.
What we must do now is that these colors are assigned to each layer separately, for that we go to the layer window and duplicate the gradient layer according to the number of base colors we have.
Then we position these gradient maps on top of each base color layer and press Adjust to lower layer.
Then in each layer of gradient we press Ctrl + E, in this way we will combine each color to the corresponding bases.
We hide the sketch layer.
We select the color pencil tool.
We create a new layer in multiply mode.
With the same color of the layer that we want to add details we will use the color pencil with a large size and we will go through the whole layer without doing much pressure, just to add texture.
We create another layer in multiply mode with the same color, now we select a much smaller size and we color as if we were doing it traditionally, with small strokes, in this way we add details.
We continue adding details in the same way with the rest of the layers.
With this we have finished our fantasy background, it only remains to add the details we want you to have.