A good starting point is to buy a couple of good books. I always recommend "Basic Electronics" by Bernard Grob and "The Art of Electronics" by Horowitz and Hill. Both are excellent books and will help you get a good start. You should be able to find them on amazon etc for a good price. However i do find that books are not always the perfect answer. There is no substitute for hands on experience. There are lots of project kits for the hobbyist which are ideal for beginners to grasp the fundamentals.
hope it helps and good luck
andy