My suggestion is to delete your existing iPhoto app.
Then go to the "purchases" tab at the App Store (as described above) and download the final version of iPhoto, which is 9.6.1.
Then, either archive that copy of iPhoto to somewhere safe on your drive (other than the applications folder), or -- just leave it in the applications folder, unused.
You never know when someday in the future, you might need to access it...