Where traditional HTML describes pages, the markup languages in the Semantic Web (XML and RDF, among others) describe things. They allow computers to understand what data means, without human intervention. For example, on a typical Contact Us page, you might see a listing of employee names, titles, phone numbers, and email addresses. They would be arranged in some sort of tabular looking list, but a peek at the code behind the page wouldn't be particularly enlightening. Codewise, a list of employees would look pretty similar to a list of products. office locations, or job openings.
A structured data list on the other hand, is tagged with descriptive labels such as first-name, last-name, tel, and email or item-name, sku, size, and price - which make it possible for a computer to distinguish between widgets and people. You've probably encountered the beginnings of the Semantic Web when skimming headlines on news sites, browsing job boards, or searching the best price for a pair of fuzzy slippers.
Well, Tim Berners-Lee (the guy who really did invent the Internet) and a bunch of other really smart people are still working out the details of how different types of data would be specified. At the moment, there are several proposed standards, plus a lot of proprietary systems used by individual publishers. In order to be truly useful, there will need to be widely adopted standards for describing and exchanging information.
Also, it can be a challenge for organizations to put all their content into a structured format. Product and contact lists are often stored in databases and easily massaged into usable files. Many news networks also keep their stories in some kind of uniform format. For everyone else, the front-end effort could be a little overwhelming. Fortunately, Cool Web Design can help.
Short answer, if you're not a millionaire right now, you probably can't. BUT - You CAN make it easier for people to find your products and services in search engines, provide content feeds to other websites (capturing still more eyeballs) and make sure you're website is ready for the future. Contact Cool Web Design for information on migrating your legacy database to the web, developing a catalog feed, or whatever other data integration needs you might have.