Try feeding a wire from the hole underneath the bridge to see where it goes - it should reach into the control cavity. If you don't put the bridge wire in, you can end up with some issues with a hum from the guitar when it's plugged in unless someone touches the strings.

The kit should have come with potentiometers and capacitors (pots and caps) in a bag with all the screws. (See the bag at the bottom left of this image - looks like the pots are in the bottom right partition of the bag).