Can someone please give me some examples of real-life use of OOP [on hold]

I recently started learning OOP, and I just don't understand how am I going to use classes and objects in real-life programming.

For example, if I'm making a note/reminders app, should I make a class, so every note or reminder is an instance (object) of this class? Or for example, if making a social networking app, making a class for a profile and when a user creates a profile, it's basically an instance of the class? I don't know if I should use classes in this case? I really need some help understanding OOP.