Your installation includes sample data, designed to show you some of the options you have for building your website. In addition to information about Joomla! there are two sample "sites within a site" designed to help you get started with builidng your own site.
The first site is a simple site about Australian Parks. It shows you you an quickly and easily build a personal site with just the building blocks that are part of Joomla!. It includes a personal blog, weblinks, and a very simple image gallery.
The second site is slightly more complex and represents what you might do if you are building a site for a small business, in this case a Fruit Shop.
In building either style site, or something completely different, you will probably want to add extensions and either create or purchase your own template. Many Joomla! users start off by modifying the templates that come with the core distribution so that they include special images and other design elements that relate to their site's focus.
The search component proviedes basic search functionality for the information contained in your core components. Many third part extensions also can be searched by the search component. Help
This module will display a search box. Help
The search component uses plugins to control which parts of your Joomla! site are searched. You may choose to turn off some areas to improve performance or for other reasons. Many third party Joomla! extensions have search plugins that extend where search takes place.