Step 1.
First of all, make a new Photoshop document with dimensions of 250x250 and a black background. Create a new layer set, name it 1b (image a) and then make a new layer inside of it. Set the foreground color to light grey (ECECEC) and the background to a darker tone of grey (8F9090). Choose the gradient tool and use it to create a reflected gradient, dragging the distnace and direction of the red arrow (image b). Use the transform (edit > transform > distort) tool to scale the bottom corners of the gradient (image c). Then create an elliptical selection and use it to cut (layer via cut) the gradient into 2.
a)   b)   c)    
Step 2.
Delete the bottom smaller part and then go to Part 2 of this Photoshop tutorial.