it's not hard. how tall is your's? with a sharp knife, cut about 4-6 inches off the top. strip the bottom 1-2" of leaves from the cutting, and stick it in the soil with the mother
plant. water as usual. in a few weeks you will notice that the original
plant has 2 or more new growths (baby
plants)
growing from the top of where you cut off the top. and the cutting will have rooted and have new growth also. at that time, you can pot the cutting up in it's own pot, and wait for the "babies" to get big enough to cut and root again.
one note though. you want to leave at least 3-4" of
plant above the soil line on the "mother"
plant.