On this video Photoshop expert Jesús Ramirez (from the Photoshop training channel) demonstrates how you can create and apply Bokeh Overlays in Photoshop.
First you need to understand that you can use almost any image as the basis for the Bokeh Overlay (Ramirez uses two smartphone pictures which are not very good just to show this). It is actually quite amazing what cool background you can get from very plain photos.
Ramirez gives us a list of steps for for this tutorial according to seconds in the video:
00:55 – Place images.
01:48 – Create Bokeh with the Field Blur filter.
02:45 – Apply overlays using Blending Modes.
03:15 – Use Levels to adjust Blending Modes.
04:00 – Use Layer Masks to hide the Bokeh effect.
06:10 – Distort images to create better Bokeh overlays.
07:30 – Composite overlays onto a photo.
09:45 – Create a sun flare.
12:08 – Use Selective Color to apply a color tone.
12:50 – Sharpen eyes with the Sharpen tool.
14:20 – Apply noise using the Lens Blur filter.