You rank up by doing training sessions, and showing the higher ups that you deserve to be ranked up. Good luck!
Assassin
AOA I
I-V
Punisher
AOP I
I-V
Medic
AOM I
I-V
Messenger
AOm I
I-V
Warrior
AOW I
I-V
Guard
AOG I
I-V
Scout
AOS I
I-V
Hunter
AOH I
I-V