There is only one forum for Shinobilegends, and you picked the right one =).
There is no pattern to when applications can be sent to be a moderator or a gamemaster.
All you need to do is, play the game, talk in the general places at least, be friendly, and be acquainted with the rules. There are more things you can do though.
When the staff thinks it is the time to have new staff members, Neji, the administrator, probably will let us know by stating it on the forums and/or in the game MOTD.