If you have just bought a SLR camera and want to learn how to take proper photos, yes, I mean turning your camera off the auto mode and finding that  M for manual, here is a book you can read in about 2 hours and it covers all the basics for you to start shooting some great shots and know what your doing.
Understanding Exposure, 3rd Edition: How to Shoot Great Photographs with Any Camera

Once, you have read this you will be on your way. For a deeper understanding I also recommend you check out his other books.