Hi Armywife,
Any issue will get you started. PhotoPlus will give you technique and ideas. I originally decided on a hard copy, but now I want digital. The main reason is that I want to be able to take all of the back issues into the field with me so that I can have it with me when I want to reference something. (My only problem is that I have a Kindle and they only offer iPod. Sigh.) To jump start you with your camera, you may want to look for the Dummies book for the 600D or one of the other books that is specific to your camera.
Photoshop is usually considered the best, however it is also the most expensive and has a high learning curve. Elements is another good one and is often used by the folks at PhotoPlus for demonstrations.
In some respects, you have a chance to set up a pretty simple studio. One or two small lights and a wireless transmitter and you are good to go. Your clients will always be in the same place (presumably your chair), so you can keep the settings the same. However, don't lock yourself into one type of photography. You will find that there are all sorts of other ways that you will enjoy your camera.
Good luck,
Frank