a) Create a new image (10X10)
b) Make a dot, with the pencil, in the middle of the square. You can use different colors for different effects.
c) Do a dropshadow on the dot. Use White as the color, around 60-65% opacity, 1 for distance, and 0 for the other 2.
d) Go to Edit --> Define Pattern --> Name it.
e) create a new shape and apply it to that shape.
Any questions?