By default, Admins have the ability to add and edit site content that most users cannot. But when you need to edit parts of the site that rarely change, it's time to turn on Construction Mode.
You can turn on Construction Mode from the main menu; it's hard to miss the big red button:
"Turn on Construction Mode" button in main menu
It'll be pretty obvious when you've turned on Construction Mode because this banner will be shown at the top of every page:
"Construction Mode is on" banner
You'll need to turn on Construction Mode if you want to: