In that case, what he means by "reboot in original firmware", is load apple's software (that your ipod came installed with) instead of Rockbox.
You do this by first turning off your ipod (hold down play until the screen goes black).
The turn it on again by pressing either menu, or select (the button in the middle of the wheel), and *immediately* you've pressed one of those buttons, flick the hold switch to the "on" position (so you can see the little red mark next to it).
That will cause your iPod to load Apple's original firmware.
Then when you connect it to your PC, you should see it pop up as a drive, and iTunes will be able to send songs to it. When you've finished copying your music to it, disconnect it safely from your PC as you would normally. Now turn the hold switch back to off again (so you can no longer see the red mark). Next, hold down both the menu and select buttons *until* you see the screen go black again. Do not let go of them until it does this. Then you can let go, and your iPod will load Rockbox again with your fresh 'n' minty music on it.