How do I get the electric pickup in my Ian Tyson Ltd to work?

I've plugged the guitar in to an amp but can't get any sound. I expect that the battery bag I found in the guitar case needs to be attached but have no clue how to do it.

To think that only six months ago we were convinced we didn't need to offer a guitar with an electric pickup. Now half of our line (2 out of 4) has electrics and by next year we'll have some sort of electric sound enhancement in every guitar we produce.

Don't get us wrong: We still think that cutting into the solid wood sidewall of a guitar to add a squirrelly black plastic battery compartment is about as tacky as it gets. Thankfully Fishman offers an alternative. Their Sonocor under saddle pickup and pre-amp has a volume and tone control that sits hidden inside the upper arch of the sound hole. The battery is contained in a bag and also concealed inside the guitar. It's held in place by a patch of velcro.
Getting the pickup to work requires:
1. Connecting the battery to the terminals on the twisted red and black wire you should see inside the guitar.
2 Putting the battery back in the battery bag
3. Attaching the battery bag to the velcro patch. That patch will be inside the guitar - either beside the volume and tone controls or glued to the neck block.
4. Test the set-up by plugging into the amp using the jack at the endpin. Don't forget the old saying "If you can't play well - Play loud!" Have fun.

You'll need to loosen or remove the strings in order to do all that high tech stuff so why not take the opportunity to change them?