I also want to learn more about graphics cards, every time I try to search for learning about either of the two though, I just get one page that teaches a small amount about CPUs and GPUs. I want to learn in-depth, but I don't want to start with something extremely complicated considering I wouldn't understand much from the get-go.
Also, I'm new here - so any general advice for this site would also be useful.
Easiest way to learn to be honest is Google the answers you want. Go through forums and read problems , read the answers experts have given and try understand why & what to do. It's easy to learn but you need to learn a bit of physics for the technical side.
Even Wikipedia will provide some decent insight into how a piece of hardware works, they'll even show you some more complex stuff some of the time. Granted, they're not really meant as a method for teaching people, as they usually don't slowly graduate from easy concepts to more complex ones.
Also books might be a better way, sometimes it's better to have a large book dedicated to a topic and can show you different concepts instead of trying to find various links on different sites.