I still don't undrstnd. What made osama to attack WTC...?

It is really good that you don't understand. Somethings are simply absurd. The real answer is that he was a bully who disliked our way of life. The old argument of all religions..."we are better than you" and " we know what is right for you" and "we will decimate you because that is what religions do..." bully and punish and overwhelm because they can.