More information on the inventory configuration section
Inventories require the dependency protocolize.
Example
inventory:# The size and type of the inventorysize:GENERIC_9X6# The title is displayed at the top of the inventorytitle:"&8&lMenu"# The items in the inventorycontent:# The slots the item will be in"top,bottom":# The material of the itemmaterial:LIME_STAINED_GLASS_PANE"center0":# The skull value of the itemskull:"<player>"# The display name of the itemname:"&a&l<player>"# The lore of the itemlore: - "&7You are amazing!"