Local Search Engine For web site

In my current web site i have very simple search engine for internal searching (ie. To search for specific page of website based on keyword enter)

In current site, i have build one database having two column
named "keyword" and "related page"

so keyword field contain list of keywords and the related page field contain page name to be displayed when specific keyword is enter..

Now i want to optimise these search engine in sense i want to make my search engine dyanamic.

so if in future i will add other pages on my site then my search engine also reflect that page if relavant keyword is enter by user.

Need help in these regards..!!!