SEARCH engines all work basically in the same way. You enter one or more "terms" or "keywords" in the space provided, then click for the engine to begin its search. Results are usually displayed according to the closest match to your terms.
The more terms you use, the better your results will be. For example, if you type in "computers" to any search engine, you will be overwhelmed with thousands of results. Narrow the search by typing "computers Apple laptops" and you will begin to find a manageable number of responses.
Or you can find something more specific again - using "Boolean operators". These are the words "AND", "OR" or "NOT" (note the capital letters). A search for "beef OR tribunal" returns items that mention beef or tribunal in any context; "beef AND tribunal returns items where "beef tribunal" as a phrase is used; "beef AND tribunal NOT bse" returns Beef Tribunal items that don't also mention BSE.
With some sites you can use quotes around a phrase to indicate you only want items with that exact phrase: "beef tribunal".
A "+" sign before a word will indicate to include it in a search, a "-" to exclude it. Thus: +beef+tribunal means only items with both words in it will be retrieved; +beef+tri-bunal -bse will exclude those which mention BSE; beef+tri-bunal will return any item with the word beef, as well as those with the word tribunal.
But that's just a start. Explore the more advanced options available on each site to refine your search even further.