I’ll collect all your questions here.
You also sent me a PM:
" Hi! I’m trying to install forge/bukkit into mineos. Need help for it 
Hi there! I trying to install modpack/plugin into mineos, but I don’t know how. I can’t find any tutorial on YouTube."
First off:
modpacks and plugins are two different things. Modpacks go with FTB (Feed the Beast / forge) style servers, plugins go with Bukkit / spogit style servers.
You can install the different server types from the profiles. FTB/Forge style is notoriously fickle to install and run, and even harder to upgrade later. Bukkit / spigot has a bug in the install for the moment, but there is a workaround here: [resolved] Building Spigot / Craftbukkit fails - solution: update WebUI
To add plugins to a bukkit server you simply copy in the plugin you want into the plugin directory for your server, and restart the server. It should then load the plugin. You may have to stop the server again to configure the plug after the first run.