The elevator car is made on one side, placed in, then other side is attached.
Small belt goes around motor pulley and yellow hub.
String goes in bushing between pulleys. Then it goes over yellow hub and down into connector in 2 by 8 plate.

The finished elevator is much like the Control Lab elevator.
Example with WeDo

 Project is on  http://ldd.lego.com/en-us/gallery
username LindaLEGOLadyHamilton

LEGO Technic Elevator - controlled by a Raspberry Pi and a PiFace Digital