So what is a blog? Blogs share ideas, report personal thoughts on different subjects and can be very useful. At the next couple websites you can look to see how Blogs are used.

http://oit.montclair.edu/documentationpdf/what_is_blog.pdf

This site teaches you to set up a blog at blogger.com. 

http://codex.wordpress.org/Introduction_to_Blogging

This site describes the differences between a blog and a course management system. 

Read through both to discover the pros and cons of blogging.