- Decide if you want to install for all users, or just yourself (this may depend on your access permissions). If you want to install for all users the Compositions folder is at /Library/Compositions/. If you want to install for just yourself the Compositions folder is at /Users/yourusername/Library/Compositions/. If the Compositions folder you want is not there, make it now.
- Quit iTunes.
- Find your new QTZ visualizer (if you need to decompress it, do so now).