There are certain things that can be done to increase your chances at showing up for certain search words and phrases. HOWEVER, no matter what is done to increase those chances, we do not have control over the search engines.
If you absolutely MUST show up for a certain search phrase, I would recommend PPC (Pay per click) using Google AdWords, Bing ads and Yahoo Advertising.
However if people are not even searching for xyz (description of your product/service and any related terms) then you still need to find other ways to increase demand. Send samples to bloggers, advertise in traditional media, go to trade shows (the list goes on.)
This is oversimplified but hopefully will help you grasp larger seo and marketing concepts that require this base knowledge. SEO is not a quick fix. Neither is building a website.
Related: SEO / SEM / PPC