sprites repeatedly falling from top of screen

Hello Everyone

I am new to app inventor, and I would like to make an app that does the following.  I kindly ask for your help and prompt response, as this is for a class and the project is due early January. Is it ight?

OVERVIEW OF APP:

My app will be a game where balls fall from the top of the screen.  The user must tap the balls the fall from the top in order to get a point.  To start with I will just have balls falling and then as you go more balls will come in and it will get faster

ISSUE(S) I NEED HELP WITH:

1.        The issue that I am struggling with having more balls fall from the top of the screen.  I was able to make one ball fall from top to bottom but I do not know how to keep infinite balls keep coming.

2.       How do I program for the ball sprite to keep falling from the top of the screen repeatedly 

I have attached my project to date

first do the tutorials http://appinventor.mit.edu/explore/ai2/tutorials.htmlto learn the basics of App Inventor, then try something and follow the

 Top 5 Tips: How to learn  App Inventor

concerning your questions:

1. hide the other balls and if you need one of them, set its visibility to true

2. you can experiment with the Ball.EdgeReached event

here might be some ideas you can use here Ryan:  http://www.appinventor.org/Chapter17     and also you could  search in the forum using the Search for topics box to the right of the colorful google at the top of this page with a term like     falling sprite    ?

Thanks All! This really helped, one day your gonna see me on top of the play store