Re: Installing ClassiPress
ClassiPress is a WordPress theme, so to use ClassiPress you need to have an installation of WordPress set up first.
If you already have your host account set up, you would install WordPress there to start with.
Once this is up and running, you would purchase, download and install the ClassiPress theme.
Once activated, you can configure your ClassiPress installation from there.
I would recommend that if you haven't had any experience with WordPress before, that you get a feel for it first before purchasing ClassiPress. You should become familiar with the process of activating new themes, do some research on how the basics work, perhaps look at some video tutorials such as ones you can find here:
http://www.maxblogpress.com/wordpresswizard20/. I think this is important as your confidence with WordPress will make it so much easier for you to get your head around ClassiPress ;)
Alternatively, you could look in the ClassiPress Theme Services thread for a coder for hire who can help with your installation, although if you plan on running the Classifieds website yourself, getting familiar with how it all works is probably a good thing.