if you look at you character sheet you see the exp.
lvl 2 you need 1,000 expgenin
lvl 3 you need 1,500 exp Chuunin
lvl 4 you need 2,500 exp
lvl 5 you need 5,000 exp special jounin
lvl 6 you need 10,000 exp jounin
lvl 7 you need 20,000 exp
lvl 8 you need 50,000 exp Sannin
lvl 9 you need 125,000 exp
lvl 10 you need 200,000 exp
lvl 11 you need 500,000 exp L. Sannin
lvl 12 you need 1,000,000 exp Kage
lvl 13 you need 2,000,000 exp
lvl 14 you need 5,000,000 exp
lvl 15 you need 10,000,000 exp
you can gain exp by every 100 posts post in the Kin topic under your name and you gain 100 exp and 100kin
a ranks give 1000 exp
b ranks give 500 exp
c ranks give 250 exp
d ranks give 100 exp
there are other requirements for rank:
Genin; joined a village
Chuunin; pass chuunin exams,
special jounin; pass jounin exams,
jounin; chakra manipulation
sannin; hav a custom made summon, hav a bloodline or specialty
Legendary Sannin; pass sanin exams
Kage; once current kage dies u take control
