CSS, how does it work?

I suck at CSS and I dunno what to do. I know the syntax, selectors etc. and have no problem coming up with a design but I srsly cannot make it work. All I want is a basic two column layout with a top and bottom and can't figure this out for shit. Does anyone have a resource for actually learning this stuff well? I mean how to actually do an effective layout, not just "hurr durr, use property a to do whatever"

Does anyone have a resource for actually learning this stuff well?

The resources are all around you, because the markup is open source. Just view the source.

There are also lots of resources on the web for CSS column layouts, because it's a common problem. It's as if you don't know how to search the internet for information. There are also many CSS frameworks available, not that I suggest that you use them.

I also have a hard time believing that you have no problem coming up with a design, because if you also know the syntax, selectors etc. then you should be able to complete this task. http://www.thegridsystem.org/