Implementing User and Password Web Site

Ok, we have a website for our club that is programmed in HTML and CGI. We want to know the process, etc. required to add the feature of having members create an account and password and then be able to access customized web pages and ordering information. Is there an easy process/program that makes this possible? What is the actual process called? Is it “account management”? I have looked through dozens of programming manuals looking for “password” or user account setups and have found nothing. Any help would be great. Thank you.