Installing Plugins
1. Find the Plugins section in the panel and find the plugins you'd like to install
2. Click on the plugin then click the "Install" button
3. Find the World Settings tab on the left and click the Save World button
4. Go to the Home tab and stop your server (wait till the status says "offline")
5. Lastly, once your server is offline, start it back up again. Once you join it your plugins should be installed
Alternatively, you can view this video
• Let me know if this helps