Choose a topic you are interested in. Acquaint yourself with the blogosphere using blog search engines to search for your topic, then spend some time reading and getting acquainted:
Here is a list of blog search engines. Go to these links and type in the topic you would like to learn about.
Technorati: http://www.technorati.com/ - indexed over 112 blogs
Ice Rocket: http://www.icerocket.com/
Bloglines - http://www.bloglines.com/
This entry on Blogging for Business belongs to Mhairi Petrovic at http://www.out-smarts.com/
More steps to follow.