Dragon fruit cuttings, also known as Pitaya cuttings are relatively easy to root. There are many methods and you can find many videos about rooting the cuttings on the internet. My preferred method to root cuttings is to place them in a pot with a moist mix of peat moss and perlite. then keep just a little moist, not too much. Although dragon fruit plants are a cactus, they are a tropical cactus, and will need more water than a desert cactus. While rooting they should be out of direct sun in some shade. If in the cold season you may need to provide them bottom heat in the form of a heat mat or some other heat source.