Step 1
Fill background with black (#000000):

Step 2
Add several lens flares (Filter>Render>Lens Flare) to your background layer:

Step 3
Add glowing edges effect (Filter>Stylize>Glowing edges) with these settings:


Step 4
Press Ctrl+U to open Hue/Saturation settings window, put a mark on Colorize and try different Hue, Saturation and Lightness settings. I always make Saturation 20 and Lightness +10. When you like a color of a background, click OK.

Here's what I've made using this technique:

Please post your results
