Welcome to LQ!
It's a lengthy work to produce a tutorial on installation of Horde on Fedora 8. If you already haven't located one by searching the web (which I assume you haven't), we'll have to wait till someone who have tried that with exact specifics answers. Or better, you can try to go ahead with the installation on your own and post the problems you encounter in the process. That way, you'll learn new trick and the members of LQ will be able to help more effectively.
Here's a link
to a tutorial to get you started. It's from the Horde wiki and guides on installation on a CentOS 5 box. I guess most of this will work on Fedora 8. And when it doesn't LQ will be here to help.