I know some keywords make more then others but what are they? how do you add or change keywords for your site?
There are different high-paying keywords for every niche. The best thing you can do is to use Keyword Elite to find the best paying keywords within your site's topic. Once you've found them, follow the tips above and use the keywords in your articles, both in the titles and the text. Just remember that human beings will read your content, and be careful - don't use too much keyword-stuffing (repeating keywords over and over again). Use your keywords to write for humans, not for crawlers. -> There was a post here talking about Keyword Elite. I don't know why it was deleted. Anyway, just Google it.
Basically, a niche is a topic on which you focus your website. If you have a travel website, you're within the "travel niche". If you have a site about tourism in the Bahamas, you're within the sub-niche "travel -> Bahamas". Other examples of niches: cooking, sports, games, celebrities. Examples of sub-niches (or narrower niches): Mexican cuisine, football, World of Warcraft, Paris Hilton. Hope this helps.