How to install Rear Light "Antique big"?

I bought the SIP 

Rear Light "Antique big" n 56015000

for my Vespa 150 Sprint, but after opening the box I realized that I have no idea about how to connect it to the cables.

I have 3 cables, 1 black, 1 blue and 1 yellow (black and blue go to the rear brake pedal) and can't understand how/where to connect them.

I suppose they have to be connected to the 2 main bolts of the rear light but in what order? also, I do not understand how is possible for the light to "understand" when is time to switch on the brake light or the tail light.

Last question guys: which bulbs am I supposed to buy for this rear light? 5w or 10w? is the brake bulb the one on the top or the one on the bottom?

Sorry for the several questions but I can't find any useful explanation on the SIP catalogue/website.

All the best