A great idea is to start with a simple tutorial to get you started http://phonuts.org/tutorials/special-effects/colourful-swirl/ then learn to modify it.
So the one above has a real funky psychedelic effect and we can work with that.
1. On your new canvas create a new layer, Layer>new layer
2. Then on you tool palette change your colours, the front say orange and your background say green. (very hippieish)
3 Then Filters>render> clouds you will end up with a layer of orange and green clouds
4. Now do Filters>distort>twirl
5. Then you do another layer above
6. Then on you tool palette change your colours, the front say purple and your background say yellow. (more hippieish)
7 Then Filters>render> clouds you will end up with a layer of purple and yellow clouds
8. Now do Filters>distort>twirl
Now for the Magic psychedelic with the Blue and Yellow cloud layer selected click on the blending mode at the top of the layers palette and scroll down to vivid light. There you have it.
And you don't have to use twirl you can use other distorts if you like and you can also change the blending mode.
One other thing you can do as well is instead of making colour clouds you can make your clouds black and white and then ad a distort. Add a new layer and put a gradient over it. It can be a linear, spherical or what ever. Pick the gradient colours of your choice and and use the gradient tool across your canvas. Then on the gradient layer add a blending mode like vivid light and there you have it psychedelic madness.
done
