Hello world!
I'm talking about how to count down in Alice3.
I've set up a scene with an alien and a UFO.
And I would like the alien to say 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 blast off!
and then the UFO is going to take off, up into the sky.

A count loop can start at 0 and end at some value.
So I'm going to use a while loop.
Before I put in the while loop,
I'm going to need a variable.
And I'm going to make it in an integer and call it num,
and give it an initial value of 10,
because that's the first value that I want him to say.
and drag in my while control loop 
and instead of just saying while(true)
what I want to do is keep going as long as num is greater than 0. (num>0)

So we're going to use our whole numbers and pick num as the first value
and 0 as the second value.
The loop is going to go as long as num is greater than zero,
the loop keeps going.

Inside the loop I'm going to have the alien say... nothing for now,
and then add to that the integer value num.
If I just left it like that he would say 10, 10, 10...
so I need to reduce the value of num by subtracting 1.
When we start with 10 and he says 10, and then num becomes 9
and 9 and 9 is greater than 0 (9>0)  and he will say 9, and so on.
Let's just run that: so far so good!

Now, when do I want him to say "blast off"?
I don't want to put the say statement to say "blast off"
inside the loop because then he would say 10 blast off , 9 blast off and so on.
So I want them to say "blast off" after the loop ends.
And  then at that point I want the UFO to move up.
Ten is probably not enough,  I want it to disappear.

So let's put in a make that a custom decimal number 
and put in something we know is going to be big enough.
Let's run it: 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 blast off!
And there it goes!
You can create all sorts of scenes similar to this one.