Ever imagined how I make those background action sequences with some lines and stuff? Well, here's how you do it in Photoshop:

1- Acquire Photoshop (use magnet to acquire Photoshop faster) (lol, enough with references)

On to the tutorial:
1- Create a new document, any square size (for example, 500x500);
2- Make sure your fore/background are default (press D to make sure they are);
3- Filter -> Render -> Fibers... and in the window play around with the values a bit. I'll use 16 for variance and 4 for strength. You can press "Randomize" in order to get a more even background (not too contrasted by a white and a black part);
4- Filter -> Blur -> Motion Blur... and in the window have a 90º angle. In distance, insert a very high number, like 200 or 300;

You have now the basic lines. You can transform them to your liking to fit the action/fighting scene they're supposed to go. To add colour, press CTRL+U, and then, with "Colorize" checked, and by tampering with the three values, you can create a brand new colour for the background. You can even tweak the lightness for a more darker or lighter scene. Have fun =P