Life became so much more simple when Photoshop CC’s Field Blur was introduced. It means you no longer have to use a combination of Gaussian Blur, layer masks, airbrush and Gradient fill to get the blurred effect that you desire.
To activate it click Filter>Blur>Field Blur, you will start with a pin that acts like a focus point for the blur.
You can click and drag this pin to any point on your image that you want to be blurred. Used on its own this will create a standard blur, but if you then click anywhere else on the image you will create another pin; if you change the amount of blurring – by dragging the circle slides around the pin – it will fade from one pin to the next.
You can add as many pins as you want, each with its own blur value, which gives you a great amount of control over which aspects of your image are blurred. This means you can ensure that viewers focus exactly where you want them to, and you have complete control over the focal point of the image.