Use NoteCase Pro's Plugin Manager (found in the "Add-ons" menu since NoteCase Pro version 3.7.5) to find and install available Plugins.
Plugin Manager automatically accesses the online Plugin feed (http://www.notecaseproplugins.com/feed) and offers options for installing, updating and removing the Plugins, which are available in the feed.
In case that NoteCase Pro does not have online access, you can download Plugin files manually from the feed and register such Plugins using the Plugin Manager's "Add Local" button.