To add to what Pete was saying, assuming you are not using a database, you could either develop a search in Perl (based on the specific fields of the site) or use something like Google.

Google provides a Free Search for searches within your site. Check out http://www.google.com/services/free.html

Also, there is some basic code you can employ from a lot of free sources. This might give you a good starting point and then you can make some changes from there.