Settings.yml is where all the magic happens.

Its where all the ranks are stored, and the respective requirements.

Below is a default settings.yml as per first instal(removal of the yml itself)

Settings:
  Ranks:
    BearCub:
      Custom-permission: 'bcranks.rankup.bearcub'
      No-purchase-perm: 'bcranks.norankup.bearcub'
      Display-Name: '&7BearCub'
      Icon: 'GREEN_CONCRETE'
      Icon-no-permission: 'RED_CONCRETE'
      Slot: 10
      Requirements:
        mcmmo:
          - 'fishing'
          - 'mining'
        mcmmocombined: 100
        jobs:
          - 'Woodcutter'
          - 'Miner'
          - 'Builder'
          - 'Digger'
          - 'Farmer'
          - 'Hunter'
          - 'Explorer'
          - 'Crafter'
          - 'Fisherman'
          - 'Weaponsmith'
          - 'Brewer'
        jobsSum: 30
        gems: 300
        money: 30000
        player:
          - 'foodlevel:15'
          - 'explevel:5'
          - 'world:resource'
      rewardLore:
          - ' '
          - '&4✇ &7Shiny new prefix!'
          - '&9Maybe more?'
      commands:
        - 'pex user %name% group set bearcub'
        - 'shout &4%name% &7just ranked up to&4 %rank%'
    Baloo:
        Custom-permission: 'bcranks.rankup.baloo'
        No-purchase-perm: 'bcranks.norankup.baloo'
        Display-Name: '&2Baloo'
        Icon: 'GREEN_CONCRETE'
        Icon-no-permission: 'RED_CONCRETE'
        Slot: 11
        Requirements:
          mcmmo:
            - 'woodcutting'
            - 'alchemy'
          mcmmocombined: 120
          money: 100000
          player:
            - 'explevel:100'
            - 'blockplaced:100'
          #This relates to the <Escape -> Stats> section of a player.
          #Please make sure the names are correct: https://hub.spigotmc.org/javadocs/spigot/org/bukkit/Statistic.html
          playerStatistics:
            - 'ANIMALS_BRED:200'
            - 'DAMAGE_ABSORBED:20'
            - 'HORSE_ONE_CM:30000'
            - 'MINE_BLOCK:100:GRASS_BLOCK'
          #Requires Quests(Build using version 3.7.8)
          quests:
            - 'qpoints:10'
            - 'qcompleted:100'

        rewardLore:
          - ''
          - 'Some more rewards here!'
        commands:
          - 'pex user %name% group set baloo'
          - 'shout &4%name% &7just ranked up to&4 %rank%'

For a full guide on setting up a rank click here.