Process:

1. I did 4 primitive pencil sketches with different positions and angles for Flash.

2. Then I scanned the 4 sketches, and decided to use the fourth sketch. I traced the Lineart over the sketch (and changed it a bit), added the details of the costume, etc.

3. In other layers in Photoshop I painted the Base Colours of every part of the costume (Red, Black, Yelloy, Skin, and  White)

4. With so much effort, I scribbled the Lightnings of the Speed Force around Flash, added some light effects to it and started adding the shadows and lights to Flash.

5. Finally, I did the background. I wanted to make the speedforce as the background, so I managed to make it as a Blue, black and white tube expanding to the horizon.

Et Voilà!

Final Product