Professional airbrushes use air tanks and compressors. The air supply is connected to the brush by a hose. You control the air through the brush by pressing a trigger button. When you press down, the air flows through the brush. When you release the button, the air stops.
Paint is sucked through the brush when air flows through it.
The paint bottles are removable so you can change colors quickly. To change from red to blue paint, for example, remove the canister filled with red paint and replace it with the one filled with blue paint. The last bit of red paint still in the brush is expelled the moment you push the button. That s why you should always spray the first squirt of paint onto a towel after each color change. Your airbrush can use paint that comes in bottles, but is must be thinned to the proper consistency first.