Best to have a strainer to hold the dried herbs.
Soak the herbs in water (can leave in strainer) for 10mins.
You can leave the more ‘runny’ herbs (e.g. seeds or powders) in sachets as below.
Start with a water level about 2 inches above the level of the herbs in the container (a rough estimate). Bring the herbs to a boil then continue on a ‘small fire’. Continue cooking on small fire until the water level is starting to go under the level of the herbs.
Then pour out the water part, leaving the used herbs in the pot. The water part is the ‘decoction’, which is a water extraction of the herbs. The herbs can be used one more time in the same way to make a second decoction, after which the herbs can be discarded.