There is no substitute for practice. My concern for people that want to jump into DSLR's is that they have little or no photography experience. Newer, modern SLR cameras have pre-sets for various conditions as well the standard P(rogram) mode, A(perature) priority, S(hutter) priority and M(anual). There are some basic photograpic tidbits that are 'almost' required to get consistent, quality results that are just not necessary in a point and shoot (range finder) type of camera. I have seen so many people that have spent good money on Prosumer DSLR's that have no idea and get upset because their expensive camera takes crappy shots compared to the cheap point and shoot they used to have. I say this as a warning to all of those who have more money than time. There no better combo than a quality DSLR/Lens Combo and experience tempered with patience.
As to your querry on where to learn. The book DSLR's for Dummies (no offense intended) is a great resource for beginner (D)SLR photographers. You'll learn how to control your images through the balance of lighting, shutter speed, aperature and ISO. Macro photography (some of the stunning imagery here) is especially demanding of experience with respect to motion(blur), depth of field(apparent amount of image in focus) and light managment. All said and done, you'll also need some knowledge of photo editing to maximize your photo skills and blow us all away with your images.
It all boils down to time & patience, time & patience, and time & patience. A little cash flow helps too.
You're doing the right thing, this is a great place to get you going. There are a lot of talented people here whom are willing to share of their experience, my kudos to reef central and its members!