Abstract background

Start by applying a gradient to the background.

Select art history brush tool from the main toolbar.
Apply settings as shown in the image.
Press F5 to open brush settings. Apply settings as shown.
Apply art history brush to the background layer.
Duplicate the layer and change the layer mode to linear burn.

From filter menu select artistic>>plastic wrap. Apply settings as shown.

Duplicate the layer. Press Ctrl+T. Right click the layer and select flip horizontal. Change the layer mode to difference.
Select and merge all the layers. From filter menu select stylize>>glowing edges. Apply settings as shown.
Press Ctrl+Shift+U to desaturate the layer.

Press Ctrl+M to open curves settings. Apply settings as shown.

Duplicate the layer and change the layer mode to color dodge.
Select the top layer in layer order in layer palette.From layer menu select new adjustment layers>>hue/saturation. Apply settings as shown.