I have attached a picture of my bubbler down below.

You fill it with water by putting water through the shotgun/carb hole on the other side of the bowl (not pictured). It's a hole, and you fill with water until I don't know, about 1/4 inch is covered with water. Enough so that it bubbles when you inhale, and the smoke goes through it. You plug the hole, let the chamber fill with smoke, unplug the hole and suck the smoke in.

I love them. They're like a corss between a bong and a pipe. Not small like a pipe, but not big like a bong, but right in the middle, plus you can fill it with water, cooling down the smoke very nicely.

I love them. By far my fav. way to smoke.