I know C++ basics enough to write basic Libraries & Wrappers when needed, but the best way to learn is by doing.
What I know (as most here can claim) they learned by determination, most have never even been to school for dev(elopment).
My opinion, Read A Book ( I am a huge fan of the Head First series, so I strongly recommend Head First C++), then practice and create applications that will make your life easier, from there you will gain the knowledge you are looking for.