This is a simple background, but it is a good simple process you should know how to do and will help you in the future. :)
Create a new file (Ctrl + N).
I am making mine 500x400 because this is for the tutorial, but you can make it any size you want.
Hit D to reset your colors to Black Foreground and White Background.
Select your Gradiant Tool (G) on the basic settings (fading foreground to background and Linear fading).
Set your Mode to Difference.
Pretty much all you have to do here is go crazy.
Try to make a few short strokes to make a few "lines". It makes the effect look more intense in my opinion.
Technically you could color it and stop here, but we are going to add a few effects.
Duplicate (Ctrl + J) the background layer we were just working on.
Go to Filters >> Distort >> Wave
Hit Randomize a few times and click OK.
Obviously after clicking okay, it is not as cool looking.
Change your mode to "Lighten" and your Opacity to around 30%
You can see that we are basically adding more "lightening" lines.
Copy the background 2 or 3 more times and do a few more randomized waves with the same opacity/lighten settings.
I did 2 more (A total of 3 layers)
You can either merge your layers now and copy that background or do what I am doing and copy the initial background and move it to the top layer.
Add a Distort >> Shear
You do not want the settings to be too intense.
Go ahead and have the same opacity/lighten settings as before.
If you want you can do a few more distort effects, but I am going to stop here and do the last few steps.
As you can see, it is a bit lighter than we are going to want.
Go ahead and flatten the image/Merge all the layers.
Duplicate the New background and set the opacity to "Hard Light".
This is just going to make it look a bit more intense.
There are many different ways we can color it, but I am going to just do a standard colorize.
Go to Image >> Hue/Saturation.
Check the "Colorize" box.
Make it whatever color you want.
As with any tutorial, you can pretty much do whatever you want. This is just a base idea to get you running through some steps.
So play around and make some nice backgrounds!
Be sure to share them in the forum. :)