Automatically display images using lightbox

I am building a blog site. Right now when an image is added to the blog article its clickable and the image opens full screen in the entire browser leaving the site and you have to click the back button to return. What I want is to automatically open the image in a lightbox everytime an image is added into the article.

Or if its not possible automatically, using a very easy way because all editors of the blog are non-computer guys and they dont know how to add lightboxes using html code.

All lightboxes I found around needs html gurus to be added...

Some help please?