To add a shortcut to a shortcuts group, perform the following steps:
Open the shortcuts group to which you want to add the shortcut.
In the folder pane, select the folder for which you want to add a shortcut, then choose File -> Folder -> Add to Shortcut Bar. The folder is added to the shortcuts group as a shortcut.
Alternatively, in the folder pane, right-click on the folder for which you want to add a shortcut, then choose Add to Shortcut Bar from the popup menu.