All is in the title..., i want to find the galaxy tab add-on for the android-sdk.
I found that : http://innovator.samsungmobile.com/cms/cnts/knowledge.detail.view.do?platformId=1&cntsId=9500 but it doesn't work
The only "GALAXY Tab" package in the Android SDK Manager is for Android 2.2 (API 8) that Google ships with the Android SDK, and as far as I can tell, it's the same as the one you can download from the link you provided.
I downloaded the package from your link and installed it in my "android-sdk\add-ons"-folder and then started "AVD Manager" and created a new device based on Target "GALAXY Tab Addon (Samsung Electronics Co., Ltd.) - API Level 8".
Everything seems to work okay for me, see screenshot of the AVD running: