Once uploaded, navigate to the FTP File Access to unzip your world.
In-game, use the following command:
/mv import [YourWorldName] [Type]
Both the name and world type will need to match the one that is being uploaded. Examples may include:
/mv import SurvivalWorld normal
/mv import MyNether nether
/mv import world_the_end end
/mv create [WorldName] [Type] – Create a specific world type on the server.
/mv import [WorldName] [Type] – Import an existing world for use.
/mv set spawn – Set the respawn point for a world.
/mv tp [Player] [World] – Teleport a player into a different world.
/mv unload [World] – Unloads a world from the server.
/mv load [World] – Enables an unloaded world.
/mv gamerule [Rule] [Value] [WorldName] – Sets a gamerule for a specific world.
Consider visiting the Multiverse-Core Command page for more information on commands and their usage.