As you add content to a guide, you are in the "authoring" mode. If you'd like to check periodically to see what the guide would look to a user, you can click the "eye" icon at the top right of the page. This will open a new tab, displaying the guide as it will be seen by users.
There are two page levels:
To add a top-level page:
Springshare help: Pages
Springshare help: Edit a page's friendly URL
To create a sub-page: