The Chooser Panel
Many actions in the CMS involve use of the Chooser Panel. The Chooser Panel has slightly different options depending on what you're doing (placing an image, moving a page, linking to a PDF, etc), but the basic operation is the same.
The Chooser Panel is displayed when choosing an asset, such as when adding an image to a page. It is a window which opens on the right side of the screen. It gives the following options to select an asset:
The Recent tab is a simple list of assets which you have recently interacted with, either you viewed them, edited them, or uploaded them. Simply select the asset you wish from the list by selecting the radio button next to its name.
The Browse tab allows you to navigate through the existing hierarchy of files in the CMS. You can navigate to the /images folder or the /documents folder, for example. Note that you need to click on the name of a folders to open it, and you need to click the radio button to the left of a file name to select it.