You visit one of these search engines at its web site and type a description of your topic into a text box using several key words. The search engine will then return a list of other web sites which it thinks will contain relevant information based on the words you typed in. As the Internet continues to grow, the information you need on a topic will probably become available. But the best these engines can do right now is offer you the opportunity to sift through hundreds or thousands of links trying to locate what you want.
Search engines cover millions of web pages.
These engines are not particularly intelligent. The pressure is on you to be VERY specific with what you want. You must be flexible enough to try lots of synonyms and you will need to understand the use of AND, OR and NOT in these search systems to save you from hours of sifting through irrelevant web links. Bookmark and use the advanced search web page. It's the only way to quickly zero in on a topic.