The very first step is to create the background gradient. Click the "Create new" icon in Layers tab, choose Gradient...

... choose colors for your gradient, style and scale (in my case, dark blue, radial, 96%).

Now I will need an excellent free fractal software called ContextFree, available at <NOBR>http://www.ozonehouse.com/ContextFree</NOBR>/ . I used it to create around 30 fractals similar to shown here.

Then copy all these fractals to your photoshop file, and distribute them around, so that they fill entire image. Then merge all layers containing fractals so that they are all in one layer.

Set this layer blend mode to overlay. If it is not bright enough, duplicate layer.