I've used two CGI books with some success:
_HTML & CGI Unleashed_ (by December & Ginsburg, Samsnet,
ISBN 0-672-30745-6), though some of it is dated.
_CGI Progamming on the World Wide Web_ (by Gundavaram,
O'Reilly, ISBN 1-56592-168-2), which covers some
material not in the former, and is probably a better
CGI book.
JLC