Composition is nothing more than a class within a class. You've already seen this when you included private member variables that were Strings. Later we'll use ArrayLists. That way we can build a more complex class out of a bunch of simple classes.
You've done a great job of creating your Car classes. Henry Ford would be proud of you. You'd have to explain to him what a computer is but once you get past that I'm sure he'd be proud of you.
Your cars and vehicles are missing one thing... Drivers, Pilots, Captains and whoever else might be in charge.
Create an abstract Person class. Then extend that class to create a Driver, Pilot, Captain or whoever is operating the vehicles you created. Add the person to your Car, Boat, etc...
Add a print statement that says the red porsche is being driven by Bob. You will get Bob from the person.getName() method.
This is called composition. Where one class contains another class.