there are mission classes, Kages will make the missions and decide how much money to give the person for each mission, players can also create missions, (send PMs to Mission receivers) Then they will PM me with who sent the mission and how much money they are willing to give for it to get completed. The money Kages give comes from the Kages Vault.
D: very easy
Genin
C: getting tougher
Genin, Chunin
B: Moderate
Chunin, Jounin.
A: hard
Jounin
S: do not do unless very experienced!
Jounin
Also to join a mission, simply post in that mission topic. If it says you need to be in a specific village, you need to be in a specific village. If you fail a mission, you will not get the money.