The advanced course

Sorry to duck out here, but one of the most useful and ingenious actions has been made and very well explained by Nate Baldwin - this is where you can have an action make any number of popup windows and create the pages for you, tailored to the size of the images you may wish to display.

Collect it here.

And ... a new addition to Nate's collection is a superb Open Window action that combines many features of the others, centre the popup, redirect the main page, it's all here. I very much recommend you download and install it right now.