Preparation
Download the plugin you want to install.
Installing Plugins
Connect to your FTP server by following the guide:
How To Edit Files Using FileZilla FTPCopy your plugin files with these extensions as follows:
*.smx to the folder
/csgo/addons/sourcemod/plugins*.cfg to the folder
/csgo/addons/sourcemod/configs*.sp to the folder
/csgo/addons/sourcemod/scriptingFor all other files, follow the instructions on the page you downloaded the plugin from.