How to change my battery on my fossil watch?

Question

No store around where I live will change the battery. They have the battery, but won't remove the back to change it. My husband has a new fossil so the back was easy to get off but I can't part with my old blue face (it was one of the last that fossil made that still had a light built in) and we can't figure out how to remove the back to even see what type battery it is, much less replace it. Then, what website can I order new batteries from