This is just an inspiration for you, creating abstract Backgrounds.
I playing around with gradients and layer modes.
You can add gradient overlays directly on the same layer or use an extra layer for it.
This is very creative technique and every result looks different.
Here is a video for you....i think you understand what i do:


Some examples made with gradients:

chris f: that's really neat! i think it was he4rty who made a tutorial here on gc on how to make patterns using gradient overlays, i must look it up!

Ah, yes i found it: viewtopic.php?f=23&t=5100
It is a similar technique.

chris f: you were a lot quicker than me there . it's obvious that playing with layer modes on gradients can give some really great results!