It sounds like you've actually bought DarkBASIC classic, which is labelled as "3D Games Creator" by some publishers. Anyway, what you need to do is download a copy of DarkEDIT (it may even be included on the CD, mine had it included) and use that to type the code with.
If you look in the Darkbasic Classic board, you'll see a stickied thread regarding the IDE. There's also a bunch of tutorials stickied there that should help your son get started. Good luck to him
CodeSurge
Version 1.0 finally released! Code your DBP projects in style.
(And save the kittens!)