To open an item: 

• PopupFolder works with all folders whether they are in the Finder or on the desktop. PopupFolder lets you access their contents immediately.
Note: To view a folder’s contents, be sure to click its icon, not its name.

• With PopupFolder, you can literally navigate through your hard disk’s contents. Normally, when holding down the Command key while pressing the active window’s title, you can access a higher-level folder window from a pop-up menu. When PopupFolder is installed, the pop-up menu becomes hierarchical enabling you to navigate through the entire hard disk.

To file an item: 

PopupFolder lets you instantly file an item found in the Finder anywhere on your hard disk. Select the icon of the item you wish to file and drag it to the first folder in the hierarchy where you wish to place it.

As soon as you put the cursor on the folder’s icon, its contents will show. Drag the mouse over the submenus until you have reached the folder in which you wish to save the item and release the button.