Blogger is just a service (free) that allows people to easily publish content to their website. This helps the sites keep fresh content on their pages, at least if you follow the idea of if it is easy to publish content you will write some everyday. Blogger automatically creates an RSS feed, in the atom format.
If you use a different type of publishing/CMS (content management system) you may have to manually configure a site scrapper that outputs your site to RSS
How will this help you promote your site? Well one thing you users could do is subscribe to the feed. As long as you update your site/feed and the user is subscribed to it, they will get the newest content. It might be an excellent fit for article/news or specials/sales.
In addition to your users subscribing to your feed, having a blog/RSS feed allows you to submit your website/feed to numerous search engines/directories just for blogs/feeds, many of these sites will count as links in the major search engines.