I know Lectora has some courses related to variables – probably some webinars or actual classes you can take. I’ll let someone else chime in on that – I’m not positive on the details. I’d recommend taking those courses to get you grounded – used to be a beginner, intermediate, and advanced course…
You have a good start – but there isn’t really a need to complicate things by having the pop-up info on separate pages – you can have it all on the same page. (show the image, hide the others essentially). I’ve mocked up your .awt with that style to get you started. You need variables to trigger so you know the user has clicked the button – that is essentially all you are doing. Then an action to hide the transparent button if those conditions are met. (Maybe someone else has an easier setup option as well).
(I also changed the type of course to a SCORM/AICC style out of habit – you can change the settings back if you don’t need this course in an LMS).