Sorry, but first you will have to make a biography, which can be done in the biography section. However even before making a biography you should go read the rules and restrictions, to even see if you're allowed to make desired biography. After reading the rules nd what not, you go make your biography. Wait for approval, and once it's approved you can go to senseis and ask for training. However you can also just do free-form Tai Ken if you want to fight other people immediatly, however Jutsu-wise, you will have to go to a sensei first, to learn jutsus. You can aswell learn Genjutsu, Strong Fist Tai and just regular Ninjutsu.
However Rain, as this training is, is not one of those normal elements you can learn, it's a ''special'' element which you need to pass a test for, before being able to have the element in your biography. And even before you can do the test you will have to have mastered Wind and Water which is one of the normal elements. Which you can learn by default, once having a biography and having a sensei to teach you.
@students; I will make the thread later, as I'm extremely tired right now, and just got home. Maybe tomorrow or later this evening.