How Whale Galleria Works:
Whale Galleria comes with a dashboard gallery generator that makes it exteremely easy to use for site admins. You can create your gallery at the dashboard, save that and then use it as a ready-to-go gallery on every page you want. These are steps to use this add-on:
1- After installing the add-on you can see a "Galleria" link in the "Files" box of your dashboard.
2- Click on the link, and you will see list of galleries already made.
3- Go to the page you intend to add your gallery, select "Galleria" block, select a prebuilt gallery and you are done.