How to install plugins on your server
Plugins need to be in .jar format to work on your server, if the file you download from Spigot or BukkitDev is a .zip, you will need to extract the file(s) before proceeding.
On the Game Panel, select "File Management" from the left navigation menu. Once you are on the "File Management" page navigate to the "plugins" folder.
From the "File Management" page in the "plugins" folder, you will see a button labeled "Upload". Click the "Upload" button and select the plugin you would like to install on your server.
Once you have completed uploading all of the plugin files, please navigate back to the "Console" from the left navigation menu. From the "Console" page you will need to select the "Restart" button for your server.
Once your server has completely restarted, you may now run the command or
pluginsin the console or
/pluginsin-game to view a list of plugins installed on your server.