Take an empty Coconut Shell

Switch on the stove flame and hold the coconut shell on flame with the help of a holder

The coconut shell partially turns black on flame and catches fire in few places. You can reduce the flame on the stove to check if the Coconut shell has caught the fire. Once done, switch off the stove and carefully move the coconut shell to a mud container or a heat proof container

Once the Coconut shell is transferred into a heat proof container, make sure you place the container in a safe place and let the coconut shell burn further into charcoal

The Coconut shell catches fire and cracks open turning red and black. Once you see that the coconut shell has opened up, you can put off the fire. I usually switch on the fan and put off the fire. 

Once the fire is put off, gather the hot Charcoal in another heat proof container carefully. 

Now you have your hot charcoal ready to use for smoking recipes