Ok, I understand where my mistake is now.

However, as Im learning the very basics of Object Orientated Pascal with all the classes and stuff, I've been learning from other programs that I found online and I try to understand how it works.

I obviously haven't managed to initialize my object properly since the error occurs everytime I try to access a variable from that class.
Here is a copy of my program:
http://files-upload.com/347054/DrawerNtWkng.rar.html
Could someone have a look (the unit having problems is 'Background') and tell me what I'm not doing properly, please?
Is it the way I do my properties? What's the proper way of doing it? Or is it just the way I initialize my variables?

Thanks a lot!