Hello,
It looks like misunderstanding. If you want to show thumbnail of image into article and display large image in the lightbox, 'System - ARI Sexy Thumbnails' plugin can be used. Install 'ARI Sexy Lightbox' module then install 'System - ARI Sexy Thumbnails' plugin. If 'System - ARI Sexy Lightbox' and/or 'System - ARI Sexy Lightbox Anywhere' plugins are installed, open 'Extensions -> Plugin Manager' page and set order values like on screenshot:
If you use WYSIWYG editor, open an article, insert large image and resize it with help WYSIWYG editor. That's all after this 'System - ARI Sexy Thumbnails' plugin creates thumbnail for large image and will display large in the lightbox.
PS: You can provide credentials to your Joomla! backend by
email and we'll help to configure the plugin and create examples.
Regards,
ARI Soft