Ok on request here is how you achieve a half tone effect here only i used the shape of a circle. If you want it around a specific shape you must copy the outline of that shape and repeat the same then increase the size of the same shape, with reversal of colors you can get different effect enjoy! Let me know if it was helpful.
If you would like to edit it change color or increase in size here is how you will expand it!
Right click the circle and ungroup select the colour you would like to change to.
Go to select > same > fill color and change to whatever which ever color you will like!
