Pages 5-7 explain how to build ships.
Systems are defined by the number of Hull Points/Spaces they take up.
Common systems (i.e Bridge, Engine, Life Support) take up no spaces.
Designed systems (i.e. AA Batteries, Guns, Missile Launchers, Shields) are chosen on a one-for-one basis (i.e. 1 Gun costs 1 Hull Space). Player decides the number and type of each system, up to the ship's maximum Hull Points/Spaces
Hangar spaces are special. They take up 2 Hull per number of Hangars chosen.