How do “dab rigs” work?

A “dab rig” is just another type of pipe with interchangeable pieces.
In a water pipe, a bowl for your smoke of choice is connected by a tube that goes into icy water inside the pipe. Once the bowl is lit, vacuum applied at the mouthpiece pulls cooled smoke through the water and into your lungs.

To begin, you will need a few tools, Torch, Water pipe, a "nail" "glass dome" dabbing picker, and Cannabis extracts, 

But, dabs of CBD or full-plant extracts use a slightly different item for the bowl, one that has to stand up to the high heat produced by a torch. The metal, glass, or ceramic “nail” is heated to red hot, then your concentrate of choice is touched to the nail.
The concentrate turns instantly to vapor and is ready to be inhaled the same way you would smoke dry herb.

Dabbing is a common popular method to get very concentrated phytocannabinoids, but the learning curve involving the heating of the dab rig, there are safety concerns and the expensive equipment requirement  make it a less accessible option for beginners. In many ways, dabbing is much healthier compare to  smoking, as there are much fewer carcinogens in it.

Dabs can be particularly potent, and are best suited for more experienced cannabie consumers. one single dab can be anywhere from 40 to 60 mg of THC per hit, depending on the potency and quality of the product, immediately being push to the brain. An important reminder is to not hold a dab hit in; exhale as soon as you’ve taken a full breath. Holding your breath at the same time that the influx of THC drastically reduces your blood pressure can result in the consumer passing out from a lack of oxygen to the brain, typically called “puff, puff, pass out.”

by the way dabbing does the same harm as smoking anything, like cigarette or cigar or use your water pipe, you are risk your self. 

In vaporizers and other tools that rely on conduction to heat cannabis to an ingestible form are placed on hot plates and heated to a very specific temperature. When dabbing, the hot plate in this scenario is an extremely hot nail brought to very high temperatures using a blowtorch, or internally heated through an automatic dab rig. The nails are typically heated to around 482°C - 538°C (900°F - 1000°F), and when concentrate such as wax is dropped on these nails, they’re combusting extremely fast.

Dabbing requires a lot of careful practice and is generally fairly dangerous due to the tools, temperatures and volatile nature of consumption involved. Beginner consumers really should consider alternative methods.

this is article write to explain ,not guide ,we not tell you to dabbing, so anything you do is your own choice.