Play with layer overall opacity.
Create another layer somewhere in the middle and fill it with Gradient (dark blue to black).

make abstract illustrations



make abstract illustrations

Add a layer mask right to this layer (Layer>Add layer mask>Reveal All).

make abstract illustrations

Use black to white gradient (black-exposes, white-hides effects).

make abstract illustrations

Well that is about it for our concept.

Final steps.

And Bevel and emboss to the biggest object (in the layer styles).
 


make abstract illustrations

Then select the round dares using the elliptical marquee tool.

make abstract illustrations



make abstract illustrations

Use select inverse command, further the selection and use blur more and Gaussian Blur Tool on the selection.

make abstract illustrations



make abstract illustrations



make abstract illustrations