Just click the green flag, and everything will start. You have to move your mouse or finger onto or across the balloons, that's how the effects work. Pop! Well you'll see.
Shout out to the program CS First, they helped me create this. I had a lot of fun making this, and I'm really happy with how it turned out. I have no idea if this will ever be seen by anyone, but I hope someone reads this. :)