okay heres a quick but effective tut for a chill out kinda backround,
1./ Open a new canvas, mine was 500x500 but you can use any size.
2./ Click and hold on the paint bucket tool until you can select GRADIENT.
3./ Set your GRADIENTS to these settings:

4./ Now this is important, you must follow this exactly, set colour mode to difference and uncheck all the boxes.

5./ Now just mess around with it i did mine using these three steps.
a./Pull the gradient from top to bottom.

b./Now pull it from the center to the left, don't worry if the colours freak out that's normal.

c./Now pull the gradient from left to right all the way, the colours will go back to normal.

and there you go you have a funky cool background,
I messed around with mine but basically that's all there is to making a sweet bg

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