The preparation is the most easy part. Simply start the server with the plugin in the plugins folder.
The plugin will make some files within his own folder inside the plugins folder. upload the MCGSetup.php file to the webserver. Note that the url to that file must be a root dir and not a subdir so for example (shop.mysite.com) is correct but (mysite.com/shop) is not.
once uploaded enter the game and join your server. enter the following command /donate admin install (with the minestore.admin permission) And follow the ingame instructions.