Ah I see. Should be fairly simple. You give each clickable area an ID which is the instance variable. Events in the sheet look like 'on object clicked (clickable sprite)' with condition 'sprite.variable=num' then you do this for each sprite in the game. On the right are the actions to perform when you click that sprite so pop up a window or text.
If you still can't work it out send a screenshot of the event sheet you've done and where it's gone wrong.