I'll help... I've done this before.
1. You need to create a character and post his bio.
There you most tell his story, abilities and characteristics.
Go to the Bio Section of Konoha Town.
2. Once you get your character approved you'll start with no training at all, exept for the basics jutsus. (All the E rank ones)
To learn more jutsus or tactics or w/e you need to talk to a sensei or a sempai.
Go to the Training Grounds Section.
3. To fight someone you can post a free challenge or accept a previous one. You can even talk to a member and challenge him/her. There are rules to fight and those are writen at the Battle Arena Rules tread.
Go to the Battle Arena Section.
4. Learn your jutsus well and fight with originality. There are plenty of jutsus and the key to success is criativity and tactics.
5. Good luck