Side view. Click to enlarge
For the cork, first make a hole in it (e.g. using a hand drill), then screw the valve (which has a thread) through it until it is completely in, then hit it through the cork by holding a screwdriver to the valve and hitting that with a hammer.
The legs we used were too short to prevent the base board from sliding when pulling the rope, but as you can see in the pictures, we solved that by putting a large (heavy!) metal plate under the whole construction. The legs then conveniently hold the board to the metal plate, and allow us to still have some room for the hose (otherwise the wooden plank would rest immediately above the metal plate!).
We noted that the metal plate sometimes was heavy to turn by pulling the cord. We remedied this by filing a corner away:
Some pics, showing nicely how everything is supposed to work:
For still more info, just look at our pictures!