If you belong to members of editor or administrator groups, you will see on the top navigation bar. By clicking this button, you will see a drop-down menu that allows you to edit content, pages and site quickly.
You can do this function only when the ACME add-on is already installed by your administrator. See here for how-to.
Simply click Content from the drop-down menu. The Edit mode will be turned on. For more details, see Edit mode.
Hover your cursor over Page, then click:
Hover your cursor over Site, then click: