What should I study to understand basics of aircraft construction?
I have seen many universities that they suggest Anderson's Introduction to Flight for the first course in aerospace engineering. This book contains fundamental aspects of the aeronautics. 

Regarding construction principles, a good knowledge of aerodynamic, propulsion, structure and flight dynamics is required before getting into aircraft design. Meanwhile, as the first step you can familiarize yourself with the anatomy of the airplane with Stinton's Anatomy of the Aeroplane, and then going to aircraft design books such as Roskam's Airplane Design Books or Torenbeek's Design book.