Assigns a thumbnail based on categoryid/thumbnail mapping to a post / page when the post is created or updated. Built-in FPW Post Thumbnails.
The plugin does not display thumbnails by itself. This is your theme's role.
IDs from NextGen Gallery must be entered with ngg- prefix, so ID 230 should be entered as ngg-230.
Upload authors' pictures into media library or NextGen gallery. File names of authors' pictures in media library must follow this naming convention: 'autor_id.jpg' where 'id' is author's user id. File names of authors' pictures in NextGen gallery must follow this naming convention: 'id.jpg' where 'id' is author's user id. The name of NextGen gallery must be 'authors'.
Look into Public method fpwCategoryThumbnails::addThumbnailToPost topic of Documentation.