UMN Search: Request a Google Search Appliance Account
With your Google Search Appliance account, a collection and front end will also be created. The collection is basically the web pages that comprise the site's search index. The front end are the configuration settings that define the presentation of the search results.
You aren’t limited to a single collection. It is very common to need multiple collections, sometimes even within the same website. For example, you might request a collection for your entire site, but you might also have a news section on your site and it's search should only display the news updates results. For the news search, you'd request a second collection that only indexes the news updates.