The Sidebar is located on the left side of your screen. By default, it's collapsed and only shows icons (this is to save screen space and maximize your working area). When you place your mouse pointer over the Sidebar, it expands to reveal a label for each navigation item.
Sidebar Shortcuts
Some icons in the Sidebar have shortcut menus to help you get to a page faster. For example, placing your mouse over the Sales button will reveal its shortcut menu.