As for the channel, make sure you have it set on 2 or 3 to pick up the
signal, you can change it by using the little black switch marked "channel
2-3" next to the on/off button. Let me know if you need more help (like
periphial sequence, etc if you intend to buy a diskdrive).
I feel that you made a good choice in giving the 400 to your son; if the
keyboard is unaltered (still membrane as opposed to having a "real"
keyboard), it is virtually kidproof. Using a joystick also improves the
fine motor skills in a child's hand (I am assuming you are giving him some
games as well) as well as hand-eye coordination.
Don't feel bad about not knowing, I was pretty dumb about certain things
when I first got my 800; I was a nintendo user in the 80's and had no idea
about the switch. Best of luck,
LykeWyse
Bob Stone