In addition to the rose essential oil and distilled water, you will also need a glass jar; if you are going to use this as a misting spray, then you will also need a misting bottle. Make sure that the bottle is made from glass or high-quality plastic. Avoid metal or low-quality plastic. Be sure to use distilled water instead of tap water; tap water often has bacteria in it. If you cannot find distilled water anywhere, then boil some filtered water and let it cool back down to room temperature. You will have to dilute this in a couple of teaspoons of vodka first or it will just float on top of the water. Make sure that you are using pure essential oil, and not fragrance oil. Fragrance oil will only give you the smell, and none of the benefits found in roses and pure essential oils. Do this for a few moment to mix the oil into the water. You can leave the rosewater in the jar, or you can pour it through a funnel into a misting bottle and use it to freshen your linens or your face.

TL;DR in Vietnamese:
Chuẩn bị nguyên liệu. Rót nước vào lọ. Thêm 12 giọt tinh dầu hoa hồng. Đóng nắp lọ và lắc đều. Chuyển nước hoa hồng vào bình đựng khác.