Start a new document any size with a white background, create a new layer called eyeball then select the "elliptical marquee tool" and make a perfect circle selection by pressing Shift while dragging the selection. Fill your selection with white color and apply these layer styles.
Your circle should now look like this.
Now create a new layer called eye, and drag a new circle selection and fill this selection with your desired eye color. Then apply these layer settings.
You should now have something like this.
Create a new layer and call this layer pupil. Use the "elliptical marquee tool" again to make a new circle and fill the selection with the color black. Then make the final layer call this layer reflection. Again use the "elliptical marquee tool" to make a circle then press "ctrl + t" to transform and rotate it like mine below.
That's it all done, now go create your self a character.