When someone uses a search engine, the results they see are ordered by a priority determined by the search engine itself.
The aim of any website that wants to be "found" through search engines is to have the highest possible page ranking for its important pages (meaning that a user is more likely to see and subsequently click on a link in a search engine to take them to your website).
Despite some claims, there is no surefire way to guarantee top page rankings across the board (if there was, everyone would do it and no-one would benefit more than anyone else) - however there are certain ways to help increase your page ranking by applying good design principles from the start.