When you are looking at the results an Internet search, you will almost always see ads first. In a Google search, the ads can be at the top of the list or on the side of the page (the areas outlined in red below). They are also marked with a small yellow Ad symbol. These websites are not necessarily bad, but you need to know that these companies have paid to have thier website be listed at the top. Google does match the ads to your search terms, but usually the companies that pay more get to be at the top. Some ads are on a "per click" basis, meaning that the companies are charged a certain amount everytime you click their link.
The sites outlined in blue are the organic search results, the results that are pulled from the Internet based on your search terms and ranked by relevance to the search term and popularity. Sometimes you will see the same website in the organic results and in the ads. It is the same link, but the link in the organic results is there because Google thought it was relevant to your search and it is a popular site, not just because someone paid to have it there.
Some search engines, like Google, can learn your preferences and start returning results that are more pesonalized if you are logged into your account. It does this based on your location and the types of searches you conduct.