Step 1:
Start by making your basic backround. In this case,it is a forest. So, I simply add the trees.
Step 2:
Add a light grey tint to all white spots(avoid the trees).
Step 3:
Using the airbrush(make the brush really big,and bring the opacity down to about 20), start shading in the picture. Be sure to make the color lighter as you get higher up. Avoid the trees.
Step Four:
Darken in the ground(using a dark blue). I recommend making the brush REALLY big(about 100). This time,make the color over the bottom of the tree trunk.
Step 5:
Make the white spots higher up the tree a little darker. Choose where you plan to make the sun,and make that darker.
Step 6:
Draw over the darker area (that you made for the sun)with pure white(using the airbrush).Then, use the straight line tool and make the suns rays(with white).
Step 7:
Go over the bottom of the trees with a lighter blue. Then, make spaces (inbetween the trees that are farthest away from the sun) a tiny bit darker.
Step 8:
Make the areas on the ground lighter where the sun would hit it.
