I have added a selection of my photos and videos to the underlying menu items. To expand the Gallery menu list click on the sign to the right of Gallery.
Some of the sub menu items in the expanded menu list e.g. Birds can be expanded by clicking on the + sign to the right of Birds.

By clicking on the thumbnails on these pages you will be shown the photo in a larger size. You can then use the left and right arrows to page through the photos within the selected gallery. By using the up arrow you will be returned to the page one menu level up.