Oddly enough, you use the video-out port and the Apple
VGA Display Adaptor that came with the iBook. Almost
any projector will have a VGA input. If you don't have the
cable, Apple will sell you one. I think there are differrent
ports/cables for the 12 and 14" models.
Then all you need worry about is sequence and resolution.
A typical projector is happy with maybe 3 display resolutions
and will show nothing if you don't set the book to one of those.
Then it's what to turn off and on in which order. It's in either
the projector's or the book's manua.