Random position generators help!

Hey, Im trying to make like a catch the falling balls game for my class assignment and its due in 2 days i need a script that is simple enough that generates a object that i have allready made and them makes it fall at different speeds. I also need a code so when my player hits the falling object it resets and goes bak to the top and falls again.
The code doesnt have to be to simple i can understand a bit of action script just stuck on this bit.