I want to make my simple search engine in my site. please advise what are the things needed to make one..
Depend if it is only to search your site pages or others sites. In the second case a 1)dedicated server 2)A spider, could be custom or one like http://lucene.apache.org/nutch/ or http://dataparksearch.org 3)A search interface I think the above one came with one.
Having a search engine is no small feet. You don't just get the tools needed, you need alot of time, and alot of ideas. I have had many search engines that do basicly nothing amazing and they have failed, I also know coding search engines without a few servers is bloody hard. The first thing to sort out is making sure you will be in profit, then the design aspects of it, then the dirty coding.
won't using google to search your site only work for pages which google has indexed itself? I've used this search engine successfully on several sites http://www.xav.com/scripts/search/ fairly easy to set up and works great.