The basics:
This is a build-your-own script, you will need to install it yourself, you will need to edit, make the site, edit the layouts, etc, etc - so be prepared for a lot of work if interested.
You download the script from here:
http://www.mysidiaadoptables.com/downloads.html
You can sign up for hosting anywhere that offers free hosting, I suggest
http://x10hosting.com/ which is what I use.
This (
http://www.mysidiaadoptables.com/for...ead.php?t=1663 ) shows you how to install it.
Once you've got it installed, you just edit the site - it's quite complicated though, and takes a lot of work.
if you are intersted, but don't like the hard work, you should try
http://myadopts.com/ which is a much easier signup-everything-is-installed site, no editing required really. It's a great place to start, and you can use the script later once you are more savvy with the script~