You will probably want to start by opening your source dir, then for each of the listings (excpet . and ..) determine if it is a directory or a file. If it is a file, copy it to the destination dir. If it's a directory, make a corresponding directory in your destination dir, open the source subdir and repeat the above steps. Sound recursive? There's a hint.

Sorry I cannot be more explicit. I've got to catch a vanpool. I'll try to check back in later and see if there are any other answers. If not, I'll bang together a few rocks and get a subroutine that'll get you started.