If you feel this was too hard for you, maybe try smaller city missions. Im sure if you play more than a few dozen missions you would start to recognize differences between vanilla expectations and when people try to do something bigger and more difficult.
What is obvious is that you didnt understand this one, which is sad, but maybe with some additional experiences in a few years you will, keep playing!
(See how dumb that sounded? Thats how you sound, relax and dont take someone's creati...