Hi Mary !
I'd start watching the tutorial videos you find here :
Then play with the tutorial files which ship with CityEngine.
Here on the Forum, many things have already been discussed, so searching a little here and there will most probably help you a lot further.
Let me know how it goes and if you have questions.
Thank you very much for your prompt and useful answer.
I've already watched some of these videos and downloaded all tutorial data and tried to work with them!
But the problem is about writhing of CGA codes based on our desire!
It's quite difficult to find some specific operations or functions among these videos! We can find them if they exist in tutorials but what about the other codes and the way of use them?
So I decided to start learning of these programming fundamentally! that's why I asked about some tutorials or books to achieve this purpose.
Anyway, that would be my appreciate if you guide me about fundamentally learning.