This depends on how your CGI program accesses the .html files; but, typically they are in whatever the document root directory is as defined in your httpd.conf (/var/www/html or some such). If you could tell us a little more about how the CGI programs access the HTML files and vice-versa, plus info on how Apache is installed (what OS, is this a personal 'public_html' directory or the global doc root?), etc., we could probably offer a little more help.
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s;;:<).>|\;\;_>?\\^0<|=!]=,|{\$/.'>|<?.|/"&?=#!>%\$|#/\$%{};;y;,'} -/:-@[-`{-};,'}`-{/" -;;s;;$_;see;
Warning: Any code posted by tuxz0r is untested, unless otherwise stated, and is used at your own risk.