If you would like to add the search functionalitiy you need to do the following:

- login as administrator
- go to administer
- go to user management
- find the search option and select the permission to search for anonymous user etc.

Before the search gives results you need to index the website, to do so go to:
- administer
- site configuration
- search settings (over here you can index your site)

Note that the search requires cron to be set up correctly.