Thank you so much Ushiro, this is my first training, so I thank you so much
Yes, sensei.
Fire Release (Katon) is one of the 5 basic nature transformations, it is made by making superheated chakra, usually from the mouth and lungs, but it can also be used on gunpowder, ash, explosive powder and throught weapons. Katon jutsus usually use the Tiger hand seal, the most commons jutsus are mid to long range technics that cause combustive and explosive damage, one of the hardest technics is to control the flames.
Fire is strong against wind, because wind increases the ammount of fire if the wind is weaker, its weaker against water, because when fire is in contat with water, the water cools it, turning into steam. Katon also can be used to generate storms, because of the heat, increasing the power of some Lightning (Raiton) technics.
Katon with Suiton makes, Boil Release, Futton, making a power vapour by the fire combusting the water.
Katon with Doton makes Lava release, Yoton, that creates lava that can be used for a lot of purposes
Katon with Fuuton makes Scorch release, a really hot chakra capable of evaporating the liquids inside the body.
Katon could be used with Raiton to have a piercing explosive attack.