Logs, large rocks, etc are things I learned in a skills class. Ned Overend's book also gives some really good explanations (with pictures) if you're someone who can read that sort of thing and translate to doing it.

I can't even remember how I really learned to ride, but the most important thing to remember is that you can always get off and walk! There's no harm in a trial run on a trail that you think is over your head - walk what you can't/shouldn't ride, and if it turns out that the whole thing is too tough you can always just turn around and go back. You may find that you can ride more than you would expect! I would chat with someone in your LBS and see if they can recommend some local singletrack that's easier.