Firstly, may I just say that the main system of choosing Bijuu is not in the players hands at all, and while this may sound slightly off-putting and power-hungry, I myself believe it would be quite beneficial to the forum if luck played a bigger part of choosing whether a player gets such a power than the players themselves.
Next, I would also like to state that the system is actually quite easy for the players to understand, and it will be easy to follow. For starters, the player simply posts their profile and then asks a current staff member to accept it. After this is completed, then the player must ask for a dice roll to find out if they are allowed said Bijuu.
And this is how you will gain Bijuu. Of course, you must also give a very good profile to be allowed to do so. The easiest way to find out if your eligible for this is to check the ranking most of the staff give you when accepting your profile, below seven means you are not, above, you are.