Before connecting the scanner to your computer, you must first open the transportation lock at the bottom of the device. There are stickers on the scanner’s case that remind you of doing that and pointing to the position of the lock.
As I said above, the Canon CanoScan 8400F allows digitizing 35mm film (in strips or in slides) and medium-format 120 film rolls. There are special holders included for all the film materials supported. The holders are handy even for very tight-rolled film.
The slide-adapter’s carriage and lamp is in the scanner’s lid. You can access it by removing the screen:
The adapter’s cable is to be attached to the appropriate connector at the scanner’s back. Once the screen is removed, you should use a holder and specify your settings in the scan program.
The intuitive driver interface is friendly to power and novice users alike, offering Advanced Mode for the former and Simple Mode for the latter. I don’t think you’ll have any difficulty mastering this software.