Some useful tips and tricks for mastering CSS is found at this site:
The one I want to study further is #10
10. PNG Fix for IE6
Yes, this is the best thing ever to fix ie6 annoying short coming (it doesn't work with background-position). However, if you want a better solution to could fix all the png images in your css files, you can try this IE PNG Fix from twinhelix and the new version support background position!
background-image: url(../img/the_image.png) !important;
filter: none !important;
When I started to learn CSS, the easiest thing I found was to create a site in HTML, using tables, and then slowly replace objects one by one. That method, above any other, was the one that really made me understand things.