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.
Step 5: Restarting 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.
Step 6: Verify your plugins have been installed correctly
Once your server has completely restarted, you may now run the command orplugins in the console or /plugins in-game to view a list of plugins installed on your server.