d I can't update it at AppStore!
The App Store should be able to update your boxed Aperture 3 version. But first you will have to upgrade it to version compatible with your system. Aperture 3.0.2 is a version released for MacOS X 10.5.
First of all, check, it Aperture has been installed in applications and not a subfolder of Applications. It should be installed directly in "Applications" and named simply Aperture.
Then go to the Support > Software Update page and download an updater. Try to update at least to Aperture 3.2.4, the last version compatible with snow leopard.
The updaters for Aperture are here: http://support.apple.com/downloads/#aperture%203
Once you have a version that can be launched on your system, enter your registration number and use "Software update" from the apple menu to upgrade to the latest version or download Aperture 3.4.5 from the support page. Aperture 3.4.5
What are your language and region settings? some posters here reported, that the Aperture updater from the AppStore will only work, if the primary system language is set to english. (System Preferences > language& Region). Reboot, before trying to update from the App Store, after changing the language.
-- Léonie