Open a new file. I used 250x250. Now make a circle with Elipsse tool. Hold Shift, to make the circle perfectly round.
In this example I've chosen red, but this can be changed to whatever you want. DON'T deselect it yet.
Now we are going to make the upper white glow. Make a new layer (Shift + Ctrl + N).
Click on the newest layer, we are going to pull a gradient through the selection. Put a simple Gradient in, from white to transparant.
Now press Ctrl + D to deselect. After that, press Ctrl + T to make it a bit smaller. Change the settings to W:80% H:60% . This will look as the following:
Now the only thing left to do is the low glow. To do this, repeat step 2 and 3. Pick the Magic Wand tool, and select the circle. Now make a new layer, and let a gradient come from below. Now you botton should look like this.
