set photo stream
I can't set the PhotoStream in preferences!!
There is no Shared Photo Stream checkbox at all in the photo stream preference pane??!
Aperture 3, Mac OS X (10.7.5)
What are your Aperture and MacOS X versions?
The Shared Photo Stream requires OS X Mountain Lion v10.8.2 or later and Photo 9.4 or later or Aperture 3.4 or later. Your Profil signature say Mac OS X (10.7.5)? If that is correct, you will have to update, to be able to use shared photo streams.
See: iCloud: Using and troubleshooting Shared Photo Streams
Regards
Léonie