Pages have editable content which you can access by clicking on the Edit button next to the page.
Pages - Adding pages
If you have a gallery page and you'd like to create sections like Portraits, Landscapes, etc it's better to create nested sets than new pages. See this article for more information.
The settings depend on the page, they include things like text, contact block options, etc. If you'd like to add images to a page follow this article.
Some templates have pages that can only be created by changing the edit mode.
Creating a page without adding to navigation
To create a page that won't appear in your site's navigation, toggle the Add to navigation switch to off when making it. This is useful when adding pages to a live site and allows you to work on the page without your visitors seeing it.You can then add the page to navigation when you are ready.