It is basically a bong without the bowl.
Instead you put the weed right into the narrow tube.No bowl no screen.
So, tear a 1/4 -1/2 inch off your cig and stick it into the hole to act as a sort of screen. The tube must be large enough to let the cig pass when you suck hard but small enough to hold it in place.
So next you put your nugget onto the cig screen light it up and suck slow and steady. Watch the smoke fill up the bottle. When the bud nug is toasted ( but the cig is NOT ) suck HARD and this will POP the cig outa the tube and let the air flow through.
The result is a sudden blast of all the smoke that was held in the bottle. Its a whole nugget/bud/dubie in one hit and it sets you right on track.

tip: change water often!