The process of creating an image gallery involves 1) creating a new page using an image gallery template, and 2) uploading the images to that page.
File import provides users the ability to upload a bulk number of files to a content Page (Name of the Image Gallery). To upload images for an image gallery ensure the target path selected is the image gallery page; this will be the parent page while the images will be the children. Image Galleries cannot read from the Media Library.
Please see the arcticle File Import for assistance:
List of Galleries is a page that hosts a number of image galleries. This page can be useful to host image galleries for various events. A List of Galleries page can contain any number of child Image Galleries, which will contain any number of child Files (images).
List of Galleries will display a teaser image and description of each image gallery. Users will need to specify the teaser and description to show correctly within the list: