You system’s first boot on its own power is what electrical
engineers call the “smoke test.” If you have any floppies in your
floppy drive, remove them. Select the “Reboot the System” menu item.
If are booting directly into Debian and the system doesn’t start up,
either use your original installation boot media (for instance, the
Rescue Floppy) or insert the Custom Boot floppy if you created one,
and then reset your system. If you are _not_ using the Custom Boot
floppy, you will probably need to add some boot arguments. If
booting with the Rescue Floppy or similar technique, you need to
specify rescue root=rootfs, where rootfs is your root partition,
such as /dev/sda1.
Debian should boot, and you should see the same messages as when you
first booted the installation system, followed by some new messages.