[Plugin: Responsive Lightbox] Show hidden content in a lightbox

Is there a way to do the following:

I want to have a sidebar-widget with a link that says something like “more” or “read on” and when you click it, more HTML content (like one or two pictures and some text) that was invisible before is shown in a lightbox.

I tried the Responsive lightbox Plugin and it shows a picture, when I click the link in my widget, but I can′t manage to define the content to be shown (the text etc)