Can you recommend me a web site providing pod-casts focused on OOP & Design?
This may be more advanced then you are after but best to get started on the right track. If you don't understand everything in here don't worry too much.
This is Scott Hanselman talking with Uncle Bob describing SOLID
http://www.hanselminutes.com/default.aspx?showID=163
You can also look at the resources avalable on Object Mentor http://www.objectmentor.com/videos/video_index.html
Have Fun!