Once you've downloaded iTunes, the installation process will start (if you chose "run" in the last step) or the installer program will appear on your computer (if you chose "save"). If you chose "save," double click the installer icon.
When the installer begins running, you'll have to agree to run it and then go through a few screens of agreeing to iTunes' terms and conditions. Agree where indicated and click the next/run/continue buttons (depending on what the window offers you).
