There are a number of details that can be added to this example. A user may want to update their entry, for example. They could do that now, but they would have to retype everything. They might also like a chance to check the results of their registration and make changes before committing them. This requires another page that displays their guest entry as it would appear on a page, and also has the fields that let them update the data.
The details of how a CGI script is hooked up with a Web server vary from server to server. You should ask your local Webmaster for help if you want to try this out on your local web site. The Tcl Web Server comes with this guestbook example already set up, plus it has a number of other very interesting ways to generate pages. My own taste in web page generation has shifted from CGI to a template-based approach supported by the Tcl Web Server. This is the topic of Chapter 18.
The next few chapters describe basic Tcl commands and data structures. We return to this example in Chapter 11 on regular expressions.