Under Add To Site in your Toolbar, you will see Add A New Sub Page To An Existing Page. You can add Sub Pages to any of the Top Level pages that you have added. All Top Level pages that you can add Sub Pages to are listed below the option Add A New Sub Page To An Existing Page. To add a Sub Page:
This is similar to the Page Options window for Top Level pages, except you also have the option to automatically create a new photo gallery to go with the Sub Page. If you choose to create a photo gallery, its default name will be the name of the new Sub Page plus "Gallery."
Your new page will have a Text Block on it, and if you choose to create a gallery, a photo gallery will also be added. The photo gallery can be changed, moved, or removed as you wish. The text you enter in the top Text Block, as well as an image if you choose to add one, will be displayed on the Top Level page as a preview of this Sub Page.
You can also add content to the page like any other page by going to Add To Page in your Toolbar.