1. Click "Quick Selection Tool" and select the main area that you do not want to apply blur effect.
(You can deselect specific area that you do not want to apply by holding alt key)
2. Click a right button of the mouse and click "Select Inverse" -> then it would select the background.
3. Go to "Filter" -> "Blur" -> "Lens Blur" -> "Adjust Radius" (highter - more blur)
