I would love to get Piwigo working as a gallery shop for photographic prints.
But so far i'm having trouble finding a clear answer as to how I should go about setting that up.

There is a Paypal shopping cart extension, but it is no longer compatible with the latest version of Piwigo.
there is also an 'add to caddie' button built into Piwigo, but i'm not entirely sure what that means or if i can edit it's function.

So my question is has anyone got a clear and simple instruction as to how to add either custom buttons or drop down menus to each image, or even better an easy to use extension that adds shop functionality to Piwigo.