Well first off as the others said you need 50 post (Genin) to make an RPG Charcter Biography. If in the bio you wan't a KG example Byakugan or Wood release you would need to fufill the requierments set for that said KG for instance to make a Hyuuga Bio you need 1500 or more. Other KG abilities have more reuqierments like a post count, Mastery over certain elements, a certain rank say Sannin, Jounin, Kage ect, and other things RP mods set by votes. Some KG abilities can only be used in NB by the characters shwon in the magna/anime meaning you can't create a a custom character for that ability an example of this is the Dust release ability which can only be used by Muu or Onoki.
As for the age, Clan and Village info heres the deal:
Age can be set up by the maker of the bio (if its custom) If its already an existing charatcer the age you put should be the one found in Wiki or in the charcters information. Example a Kakashi Bios age should be 30 if you decide to make it in this time. As for a Custom Bio the age can be set by you.
Clan set up has to be either the clan of said Charcter. If you decide to make a Custom Hyuuga Bio his clan is the Hyuuga, same goes for Uchiha and other clans found in the manga,anime. Some Bio's here in NB have made up clans which can be created by NB Official Sage's Like the Kyioshi or Nekura Clans. Only if one gets accepted in those Custom clans by there leaders can you have a Biography consiting of them. If your character belongs to no custom clan or existin clan it should appear in your Bio as N/A.
And for the Village Info: The Village of birth doesn't exactly have to be a ninja Villge some people place in thier bios (Was orned somewhere in the Fire Nation) Or something like that. As for the Village of alliance you must put their your official village in NB example My NB Village is Kumo so thats my Village of Alliance. (I'm not sure if one can have more than I Village of alliance though some ppl do put Social group that RP in that part also).
And Finaly the Rank that one places in the Bio is your NB Post rank. meaning that if your a Genin your Bio rank is automaticaly Genin, same as if your S-Class-Ninaj the bio rank is S-Class. Hopes this helps ^^
