Admins can add a photo gallery module to any static page. Just select the photo gallery module from the Add Module drop down.
By default, modules may be closed. To expand & work on a module click on the + symbol next to the module.
You can move content modules up & down by clicking on the move up / move down buttons (make sure you save the page after you reorder a module).
Add photos using the image picker by selecting the add new media button.