I will do my best, sempai :worshippy:
Ninutsu: I as term, meaning Ninja Techniques, wich are unique abilities that vary from every ninja. Ninjutsu includes the usage of the five elements, Kekkei Genkai(a combination of two elements, and sometimes bloodline connected jutsu), Kekkei Tota(combination of three elements). Genjutsu is also included as a ninjutsu. Genjutsu is a power to manipulate the 5 senses that either the user, or the opponent may use in battle. Kenjutsu, is the usage of swords, and other weapons. Ninjutsu is almost always reliable from hand seals and chakra.
Chakra: Is a form of energy, that all ninjas use in their battles(atleast all ninjas who choses to). Upon battles, ninjas may gain experience to create even more powerfull jutsus, and gain wisdom. When a ninja is skilled enough, they can take the advantage of their chakra, by manipulate it to their liking. Giving the ninjas the ability to walk on water, and even climb on trees by only using their feet.
Katon/fire, is one of the five nature based elements. The Uchiha clan are all very skilled with the Katon. The Katon can also be used in Kekkei Genkais, as in Lava release(Katon + Doton(earth release)), Boil release(Katon + Suiton(water release), Scorch release(Katon + Fuuton(wind release)), and the most devastating of them all. The Kekkei Tota, Dust release(Jinton, Katon + Fuuton + Doton).
Katon's strength is against Fuuton aka Wind release, and it's weakness pretty much says it itself, the Suiton aka Water release.
I have stated all except the Raiton, the Lightning release. Wich also is a great feature of the Uchiha clan. If you want to hear again, i'll list them up:
Katon/Fire release.
Fuuton/Wind release.
Doton/Earth release.
Suiton/Water release.
Raiton/Lightning release.
Hope i did well, sempai :y