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Create a new document (1000*600 pixels)
Make a selection using Rectangular Marquee Tool.
Select the Subtract from Selection option in the options bar, and drag to intersect with other selections.
A minus sign appears next to the pointer when you’re subtracting from a selection.
Choose Select > Modify > Smooth.
Smooth Selection: Sample Radius 10 pixels.
Click Ok.
Create a new layer.
Fill selection with blue color.
Create a new layer.
Click on "D".
Choose Filter > Render > Clouds.
Filter > Render > Difference Clouds.
Click Ctrl +F several times.
Filter > Blur > Gaussian Blur.
Filter > Sketch > Chrome.
Choose Soft Light Blending Mode from the Mode pop‑up menu in the options bar.
Choose Navigation bar layer (Layer 2).
Select > Load Selection.
Create a new layer.
Fill it with Linear Gradient (blue/white)
Transform layer with gradient using Free Transformation just like in the example below.
in the options bar, and drag to intersect with other selections. 
