How to Add Pagination to Your Gallery

1. Click Photo Gallery from the menu on the left of your WordPress dashboard. 
2. From the list under Photo Gallery, click Options, then click the Gallery defaults tab.
3. From the window that follows, find the Pagination setting under your gallery’s layout, and click the type of pagination you want to add to your gallery.
4. Click the Save button at the top right to save your settings. This will apply your selected option to every gallery that uses default options.

In order to apply this setting to a single specific gallery click the shortcode of the published gallery in your editor, uncheck the box next to Use default options, then follow step 3 and click Update.

There are 3 pagination types to choose from:

1. Simple: adds a simple current/total page number counter, next/previous page buttons, as well as first/last page buttons.
2. Load More: adds a Load More button that loads a set amount of images when clicked on. You can set the number of images that load from the Images per load option from the same window.
3. Scroll Load: this pagination type loads new images by simply scrolling down.

To allow pagination on your gallery make sure the number in the Images Per Page option is less than the total number of images displayed in that gallery.