I think any photographer, if they were to look at their work from a year ago, will see things they wish they'd done differently, and (hopefully) know how they would improve it if they were to reshoot it now. That's a good thing, its progress.
Learning your camera settings is definitely very important,,and both studying the manual and classes can be very helpful, but neither will really be of use if you don't get the camera in your hands and start fiddling with stuff. Every camera will have an option to reset everything to the factory defaults, so there shouldn't be too much concern about screwing stuff up while experimenting. On the other hand, its not much use to just madly change settings and shoot pictures, you need to experiment with a purpose in mind, and monitor what you are changing, how much, and the effect on the images.
As far as online course, if you like that sort of thing, I can't recommend www.creativelive.com
enough - they offer entirely free, live, interactive courses with some of the best photographers out there. They also record all of them, and offer the videos afterward for a fee. I've watched many of their classes, and they are invariably excellent. Do yourself a favor and check them out if you aren't familiar with them yet.