Reading your dog's signals can be confusing. When first starting to learn, start by breaking it down into each body part - then look at the whole picture! Only basing an interpretation on one body part can be misleading, as sometimes it takes looking at everything together. For examples of body language along with pictures, please check out the sites below:
Paws Across America; How to Interpret Your Dog's Body Language, Facial Expressions, and Vocalizations: http://www.pawsacrossamerica.com/interpret.html
Carol Byrnes; Reading Dog Body Language: http://www.diamondsintheruff.com/diagrams.html
APDT Website; Dog Park Body Language: http://www.apdt.com/petowners/park/bodylanguage.aspx
There are also several books and DVDs on dog body language...
1. Aloff, Brenda. Canine Body Language: A Photographic Guide to Interpreting the Native Language of the Domestic Dog.
2. Rugaas, Turid. On Talking Terms With Dogs: Calming Signals.
3. Kalnajs, Sarah. The Language of Dogs (DVD).
And many more...!