Migration from Object Based Environment to Object Oriented Environment

I am a freelancer. I have developed Five Software Applications (windows based) with the help of VB.NET. I know that by default all the .vb files create there own Classes and .NET Environment itself create several classes on its own. But in any of my Projects I have not created a SINGLE Class of my own.
In this kind of scenario what I felt that I am using OBJECT BASED APPROACH rather than OBJECT ORIENTED APPROACH. I have developed projects like Student Management System, Accounts Management System for Trading Business etc. My next project is LIBRARY MANAGEMENT SYSTEM. I want to do my next project in Object Oriented approach.
I will be very much helpful if any body helps me in this regard. I just want to know the ways of Object Oriented Approach keeping in view of LIBRARY MANAGEMENT SYSTEM. What are the ways from where I shouls start ?????