Have a word with your web host.
Most web hosts offer a few simple preconfigured CGI scripts and the most common are form to email (feedback form), guestbook, forum, counter and time and date. Some hosts offer others, some offer nothing at all, but most will have some simple scripts along the above lines that you can configure through your hosting control panel to do the job.
One alternative you could do is to create a frame on the main portion of your site and link your Angeltowns guestbook into the frame.
Beyond that, you'll need to either download one of the free guestbooks online; go to Google and type
for more information than you probably want. Note that any CGI application assumes that you have access to your web CGI bin and that you are allowed to run custom scripts from it.
An alternative would be a PHP guestbook. Some of the off the peg guestbooks on the web allow you to use underlying flat files rather than MySQL so you don't need a MySQl database, but you do obviously need PHP support on your web account.
Go to Google and type in this:
Aside from that, I haven't a clue. I don't use guestbooks so although I know how and why they work, that's about the limit of my experience with them.