Although simple conceptually object orientation needs a serious amount of experience to be fully appreciated. It represents a major paradigm change from procedural programming. The following links can help you to get started.

Have a look at relevant OOPSLA tutorials. Make sure to check the Cetus links. A good place to spend some time reading interesting OO concepts is the Taligent Online Books.

Also, remember to check Brad Appleton’s OO Page and Cetus for various OO resources.

Have you read the Cathedral and the Bazaar ?