OK- here's the deal- How are your powers of make believe? Because I didn't think to get a picture of the plug all by it's lonesome before adding the cording.
So let's all pretend there ISN'T a gold cord attached!
Open the plug by removing the two screws. The black thingy will slide off and you can now grasp the yellow thingy.
(and, if you enjoy this picture- you're in luck -you'll see it again at the end- but don't even think about that right now)
Now thread the black thing (round hole in back/rectangular hole in front) onto the cord with the rectangular opening toward the end where the wires are. (photo 3 in Chandelier 8 if you need a another visual)