How do I make a shop that changes the effect?

To make it simple could anyone tell me how to make a shop that would change the effect on a ball. So the ball is the player and it starts out black. But i want them to be able to go to the shop and change the color or effect on the ball.

I am not sure what you mean by "to the shop" thing, but you can change the look of any Sprite object either by using different frames that you've prepared earlier (frame 0 = Black, frame 1 = Yellow, ...etc), or use a webGL effect like Tint, AdjustHSL or Set Color, and set the parameters with events and actions.