First thing you will need is your own domain and hosting account Click Here for more details. Once you have a presence on the web you will need to build a site the easiest way is through your control panel through your hosting account most provide you with a step by set site set up wizard.
Alternately you can download a wordpress blog the preferred blog on the internet see sources for details. This is easy to install with a remarkable 5 minute install.
Personally go with the blog as it more SEO than a site due to the content update factor. Plus with all the additional plug in these sites can become awesome.
Once you site/blog is built you will need to apply to Google for a adsence account. You will be required to give them the url of your site so they can check it out. So have some good content on there the better content the greater chance you have at being accepted.
You can also place affiliate links and banners on your site these will bring additional income through the commission you will gain from sales you generate. clickbank is a good one as well as commission junction. These two places handle everything including your payment.