How do you use flame alchemy?

Answer 1

to perform flame alchemy use gloves Made of "pyrotex/ignition cloth" and embroidered with unique flame alchemy Transmutation Circles, these gloves create a spark when Roy rubs his fingers together and allow him to manipulate the concentration of oxygen in the air surrounding his target, raising its density to a level at which it becomes a volatile and flammable oxidizer, and creating narrow pathways of oxygen through which he can direct the ensuing flame that blossoms from the spark. The 'snap' sound is caused by the instantaneous speed at which the highly concentrated gases and sparks react together and pop (not his fingers actually 'snapping', to common belief.)

While Mustang's Flame Alchemy cannot be used on rainy days because the humidity makes it impossible for his gloves to produce sparks, it becomes clear that water itself does not make the Colonel entirely as "useless" as his subordinates assume. Using the transmutation circles on his gloves, Roy is able to separate hydrogen atoms from the oxygen atoms in water molecules, isolating them into a highly combustible fuel and powerfully volatile oxidizer, respectively. Though this method can only be used when a large quantity of water is present in a relatively closed-off space (and not in the rain where the air is open and separating hydrogen and oxygen for the purpose of combustion would pose far too much danger to anyone in the vicinity), with an outside source of ignition such as a cigarette lighter or a match, Roy can produce extremely powerful, localized explosions.

it is indeed very hard good luck