You can use two types of gallery: the WordPress gallery or a gallery with thumbnails.
WordPress gallery
Use the building shortcode « gallery » or click the « Add Media » button to create a gallery.
Gallery with thumbnails
[thumbnails_gallery images_from_media_library= »image-1,image-2,image-3″]
[[thumbnails_gallery images_from_media_library= »image-1,image-2,image-3″]]