Since the name of the folder has a
. in front of it, it is hidden by the file manager. All files and folders that have a period as the first character in their name will be automatically hidden by file managers. To see them, you usually have to enable the viewing of hidden files and folders, which can typically be done using a simple keyboard shortcut. The keyboard shortcut in the default Gnome file manager is Ctrl + H. Press the keyboard shortcut to see hidden files and folders, press it again to hide them again.
So to navigate to that particular folder, open your home folder (go to the launchers on the left and click the folder) and press Ctrl + H. Then you will see, in the list of files and folders,
.sabnzbd. If you don't want to see all of your hidden files and folders again, press Ctrl + H while the window is still open.