Tie them up and hang them upside down in a clean paper bag in a warm room until dry. Once dried, crumble them up and put in a sterilized lidded jar and label clearly. You should buy boxed tea bags from a shop that has a quick turnover and not where the products may have languished on the shelves for a long time losing their power and flavour. The first thing which must be said about growing herbs yourself which you intend to ingest, is to make absolutely sure the plants are what you think they are, especially if a pregnant woman is to partake. They should be careful about checking to see what effects the teas will have before imbibing.
Many plants look the same, eg.
To make a tisane you use the infusion method, which consists of cleaning and chopping the chosen herb or flowers, covering with boiling water and placing a cover such as a saucer over the receptacle for a few moments. This will allow the juices to flow from the plant tissues into the hot water, yet keeps the liquid separate. When the perforated part is loaded up with the herb and snugly secured into the pot, hot water is poured over the plant material, the lid is put in place with the plunger in the 'up' position. Wait for the infusion to reach the desired strength and then slowly press the plunger down. This action will stop the infusion getting any stronger as it will squeeze out the plant.