Hit CTRL+D to deselect. Then go to filter > Blur > Gaussian Blur and pick the radius like 20-24px to get effect below. Also change layer's blending mode to Color dodge or Screen.

Now pick the gradient tool (same color and same gradient settings as above), but this time instead of linear, select radial gradient. Make a gradient as arrow below shows and change its blending mode to Vivid Light.

Pick soft brush (pretty big diameter, like 200 or 300px, 75% opacity), select some blue color like #1b31a6 and paint on the bottom part of header. Then change this layer's opacity to 30%-40% and blending mode to Pin Light.

Add some lines with semi-soft brush. I actually used my custom brush, but it is mostly the same- it's just not round. Then make this layer 65% opacity and change its blending mode to Overlay. Thanks to this small details we will add some randomness to the lights on the header so we will hide the simplicity of gradients.

Step 9 - Stripes&Circles

There aren't a lot of philosophy in here. Firstly, pick the Polygonal lasso tool, hold SHIFT and make a diagonal line from top to bottom. We are holding SHIFT so the line is inclined with exact angel of 45 degrees. Hold SHIFT until you will create a shape like this:

I shouldn't say that on this level, but above all I will: remember about new layers. Every stripe on separate layer. Alright, fill the selection with white color and change it's blending mode to Overlay and opacity to 10%.

For next stripes I will just write down the color, blending mode and opacity. Here it is Gray color (like #7f7f7f), Luminosity, 12%. As you can see this stripe partially covers the one created before.

Color #191813, Multiply, 16%.

Color white, Overlay, 100%.

The whole layout looks like this for now, now we will continue with stripes aimed in the reverse direction.

Color white, Overlay, 5%.

Color #7f7f7f, Luminosity, 4%.

Color #191813, Multiply, 7%.

Color white, Overlay, 22%.

The perceptive one can see that I just flip horizontally previously made stripes and lower down their opacity, but actually to get better effect it is good to create every stripe separately. Alright then, let's head to the circles. Pick the Ellipse tool and with SHIFT (so we will get perfect circle) make a shape like this. You can additionally hold ALT so instead of the corner, your shape will be sized from the center. Use white color and lower down the opacity to 15% with blending mode set to Overlay.