1. Create a gradient with one light and one dark tone of the same color, as you can see I've chosen red. 2. Make a round selection using the Marquee Tool, if you want it circular hold down the Shift key while making the selection. 3. Now use the Gradient Tool and make a gradient in the selection. 4. Create a new layer and make a selction that's a little smaller than the first one and use the Gradient Tool to create a gradient in the opposite direction. Merge the layers down and we're finished.