Image Sprite and FOR

[masc72]

Hello everyone,
I'm sorry for my english.
I have a problem in my game:
I have 5 image sprite (ball 1, ball 2, ball 3, ball 4, ball 5)
then, a sprite image that has the function of "add",
if I touch image sprite "add"
appears 1 ball,
if I push one more time appears ball 2,
and so continuing,
after I will create a sprite image "remove"
it will inverse (if there are 5 balls it takes away one at a time).
I'm using App Inventor classic,
anyone can help me to develop the loop FOR for this problem?

thanks