eta... don't need to know about exposure, dof, all that - I've shot hard film for years, and understand the concepts. Everything was manual back then! I need to know how all the little buttons work!
Depending on your model camera, you can look for the books by David Busch. He writes books which, effectively, are like an owner's manual in that they are written for a very specific model camera and not generally for just any DSLR or even any "Canon" DSLR, but they go into more detail. He describes the features and gives examples in more depth than you'd find in the owner's manual.