Just put the battery in the holder and push the lock back in it's place. On this model there is a big sticker about the reset procedure. I can recommend to do this after every battery change. Possible indications that the reset procedure is forgotten are: strange digits, the EL stays on or sometimes the module works but suddenly dies within a few days. For the Reset procedure you need to locate the AC contact.
You need to short circuit the contact and the back of the battery (+). Best to use your sharp tweezers, but if you are inventive, you can use other metal objects too (two watch screwdrivers, fold open staples, paper-clip, etc).
Horology Crazy weblog. Thanks to him I can add some new battery change nomenclature to my vocabulaire. Thanks!