Step 5: Add the battery holder an the switch
Solder the black wire of the battery holder to the lead of the capacitor that is the closest to the grey stripe.
Solder a piece of wire to the other lead of the capacitor.
Then solder the push-button switch to the red wire of the battery holder and the other wire.
Also, the battery holder you just added, that is where you put the dead Ni-Cad battery to zap them.