No. You may or may not need it. It all depends on the goals of the application and the requirements.
The question "how to study" is too broad. Perhaps you can find the best answer in this most inspirational reading:
Peter Norvig, Teach Yourself Programming in Ten Years,
http://norvig.com/21-days.html[
^].
[EDIT]
This should explain why I say that there is nothing object-oriented in this question (please see my comment to the question): using the notion of "class" or this keyword along does not make programing object-oriented. Real OOP starts when
late binding is introduced, not sooner.
Please see
http://en.wikipedia.org/wiki/Object-oriented_programming[
^] — data abstraction, encapsulation, messaging, modularity, polymorphism, and inheritance are just the essential prerequisites.
Eastern proverb say:
Saying 'halva-halva' won't make your mouth sweet.
See also:
http://en.wikipedia.org/wiki/Late_binding[
^],
http://en.wikipedia.org/wiki/Dynamic_dispatch[
^].
—SA