You can use void when a method doesn't return anything. The name of the method. The parameters of the method. The body of the method. We tend to classify methods as observers and modifiers.
Observers extract a value from the object without changing the object.
Modifiers change the object. Constructors Constructors are special methods used to create new objects within the class. They are much like methods except that you don't include the type. Whenever you build a new object in a class, you call a constructor. Just so you know what you're getting into, I've put together a small chart comparing Scheme to Java.