Matt's Script Archive Simple Search allows you to integrate a keyword and boolean search program into your site so that users can search specified text and HTML documents. It then returns a list of file names (displayed based on their title tag found in the HTML page) which matched the specified keywords.
The Readme files at Matt's Script Archive contain detailed installation, configuration and usage instructions that will take you step by step from putting the scripts on your system to using them in your web pages. You should read these through and keep them by you when setting up or installing any MSA script. It is probably not a bad idea to print them out.